RESUMEN

B cells and dendritic cells (DCs) each develop from poorly described progenitor cells in the bone marrow (BM). Although a subset of DCs has been proposed to arise from lymphoid progenitors, a common developmental pathway for B cells and BM-derived DCs has not been clearly identified. To address this possibility, we performed a comprehensive analysis of DC differentiative potential among lymphoid and B lymphoid progenitor populations in adult mouse BM. We found that both the common lymphoid progenitors (CLPs), shown here and elsewhere to give rise exclusively to lymphocytes, and a down-stream early B-lineage precursor population devoid of T and NK cell precursor potential each give rise to DCs when exposed to the appropriate cytokines. This result contrasts with more mature B-lineage precursors, all of which failed to give rise to detectable numbers of DCs. Significantly, both CLP and early B-lineage-derived DCs acquired several surface markers associated with functional DCs, and CLP-derived DCs readily induced proliferation of allogeneic CD4(+) T cells. Surprisingly, however, DC differentiation from both lymphoid-restricted progenitors was accompanied by up-regulation of CD11b expression, a cell surface molecule normally restricted to myeloid lineage cells including putative myeloid DCs. Together, these data demonstrate that loss of DC developmental potential is the final step in B-lineage commitment and thus reveals a previously unrecognized link between early B cell and DC ontogeny.

Asunto(s)

Subgrupos de Linfocitos B/citología , Células Dendríticas/citología , Receptores de Hialuranos , Glicoproteínas de Membrana , Envejecimiento/inmunología , Animales , Subgrupos de Linfocitos B/inmunología , Subgrupos de Linfocitos B/metabolismo , Células de la Médula Ósea/citología , Células de la Médula Ósea/inmunología , Células de la Médula Ósea/metabolismo , Antígenos CD4/biosíntesis , Diferenciación Celular/inmunología , Linaje de la Célula/inmunología , Células Cultivadas , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/inmunología , Células Madre Hematopoyéticas/metabolismo , Inmunofenotipificación , Antígenos Comunes de Leucocito/biosíntesis , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Proteínas Mitocondriales , Receptores de Complemento/biosíntesis , Receptores de Interleucina-7/biosíntesis

RESUMEN

Notch signaling regulates cell fate decisions in multiple lineages. We demonstrate in this report that retroviral expression of activated Notch1 in mouse thymocytes abrogates differentiation of immature CD4+CD8+ thymocytes into both CD4 and CD8 mature single-positive T cells. The ability of Notch1 to inhibit T cell development was observed in vitro and in vivo with both normal and TCR transgenic thymocytes. Notch1-mediated developmental arrest was dose dependent and was associated with impaired thymocyte responses to TCR stimulation. Notch1 also inhibited TCR-mediated signaling in Jurkat T cells. These data indicate that constitutively active Notch1 abrogates CD4+ and CD8+ maturation by interfering with TCR signal strength and provide an explanation for the physiological regulation of Notch expression during thymocyte development.

Asunto(s)

Linfocitos T CD4-Positivos/citología , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Proteínas de la Membrana/metabolismo , Proteínas Nucleares , Receptores de Antígenos de Linfocitos T/metabolismo , Receptores de Superficie Celular , Animales , Antígenos CD/metabolismo , Antígenos de Diferenciación de Linfocitos T/metabolismo , Linfocitos T CD4-Positivos/inmunología , Antígenos CD5/metabolismo , Linfocitos T CD8-positivos/inmunología , Proteínas de Unión al ADN/metabolismo , Citometría de Flujo , Regulación de la Expresión Génica , Antígenos de Histocompatibilidad Clase I/inmunología , Antígenos de Histocompatibilidad Clase I/metabolismo , Antígenos de Histocompatibilidad Clase II/inmunología , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Células Jurkat , Lectinas Tipo C , Hígado/citología , Hígado/embriología , Proteínas de la Membrana/genética , Ratones , Ratones Transgénicos , Factores de Transcripción NFATC , Regiones Promotoras Genéticas/genética , Receptor Notch1 , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/inmunología , Elementos de Respuesta/genética , Transducción de Señal , Timo/citología , Timo/inmunología , Timo/metabolismo , Factor de Transcripción AP-1/metabolismo , Factores de Transcripción/metabolismo

RESUMEN

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the function of cyclooxygenases, COX-1 and COX-2, which catalyze the first step in the synthesis of inflammatory mediators (PGE2). We sought to understand the roles of cyclooxygenases and NSAIDs in T-cell development. Our data show no significant defects in T-cell development in fetal thymic organ cultures of mice disrupted in both or either COX genes or in mice disrupted in either EP-1 or EP-2 receptor genes. On the other hand, NSAIDs reproducibly caused thymocyte developmental defects. However, the specific effects of the COX-2 inhibitors were not correlated with their potency for inhibition of COX-2 activity. We focused on the NS-398 COX-2 inhibitor and showed that its effects could not be reversed by exogenous PGE2. Furthermore, NS-398 was inhibitory even when its target, COX-2, was absent. These data show that the T-cell developmental effects of NS-398 are COX-2 and PGE2 independent.

Asunto(s)

Antiinflamatorios no Esteroideos/toxicidad , Inhibidores de la Ciclooxigenasa/toxicidad , Dinoprostona/fisiología , Síndromes de Inmunodeficiencia/inducido químicamente , Isoenzimas/fisiología , Nitrobencenos/toxicidad , Prostaglandina-Endoperóxido Sintasas/fisiología , Sulfonamidas/toxicidad , Linfocitos T/patología , Timo/patología , Animales , Antiinflamatorios no Esteroideos/farmacología , Ciclooxigenasa 1 , Ciclooxigenasa 2 , Inhibidores de la Ciclooxigenasa 2 , Inhibidores de la Ciclooxigenasa/farmacología , Dinoprostona/farmacología , Indometacina/análogos & derivados , Indometacina/farmacología , Indometacina/toxicidad , Isoenzimas/antagonistas & inhibidores , Isoenzimas/deficiencia , Isoenzimas/genética , Proteínas de la Membrana , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Ratones Noqueados , Nitrobencenos/farmacología , Técnicas de Cultivo de Órganos , Prostaglandina-Endoperóxido Sintasas/deficiencia , Prostaglandina-Endoperóxido Sintasas/genética , Receptores de Prostaglandina E/deficiencia , Receptores de Prostaglandina E/genética , Subtipo EP1 de Receptores de Prostaglandina E , Subtipo EP2 de Receptores de Prostaglandina E , Sulfonamidas/farmacología , Tiofenos/farmacología , Timo/embriología , Timo/inmunología

RESUMEN

Hox homeobox genes play a crucial role in specifying the embryonic body pattern. However, a role for Hox genes in T-cell development has not been explored. The Hoxa-9 gene is expressed in normal adult and fetal thymuses. Fetal thymuses of mice homozygous for an interruption of the Hoxa-9 gene are one eighth normal size and have a 25-fold decrease in the number of primitive thymocytes expressing the interleukin-2 receptor (IL-2R, CD25). Progression to the double positive (CD4+CD8+) stage is dramatically retarded in fetal thymic organ cultures. This aberrant development is associated with decreased amounts of intracellular CD3 and T-cell receptor beta (TCRbeta) and reduced surface expression of IL-7R and E-cadherin. Mutant thymocytes show a significant increase in apoptotic cell death and premature downregulation of bcl-2 expression. A similar phenotype is seen in primitive thymocytes from adult Hoxa-9-/- mice and from mice transplanted with Hoxa-9-/- marrow. Hoxa-9 appears to play a previously unsuspected role in T-cell ontogeny by modulating cell survival of early thymocytes and by regulating their subsequent differentiation.

Asunto(s)

Apoptosis/genética , Genes Homeobox , Proteínas de Homeodominio/genética , Linfocitos T/patología , Animales , Diferenciación Celular/genética , Linaje de la Célula/genética , Regulación del Desarrollo de la Expresión Génica , Ratones , Ratones Noqueados , Timo/embriología , Timo/patología

RESUMEN

Several homeobox genes of the HOXA and HOXB clusters are expressed in primitive blood cells, suggesting a role for HOX genes in normal hematopoiesis. The HOXA9 gene is expressed in CD34+ marrow cells and in developing lymphocytes. We examined blood-forming organs of mice homozygous for an interrupted HOXA9 allele to determine if loss of HOX gene function is deleterious to hematopoiesis. HOXA9-/- mice have approximately 30% to 40% reductions in total leukocytes and lymphocytes (P < .001) and a blunted granulocytic response to granulocyte colony-stimulating factor (G-CSF). Homozygous mice have significantly smaller spleens and thymuses. Myeloid/erythroid and pre-B progenitors in the marrow are significantly reduced, but no significant decreases are noted in mixed colonies, day 12 colony-forming units-spleen (CFU-S), or long-term culture-initiating cells (LTC-IC), suggesting little or no perturbation in earlier progenitors. Heterozygous animals display no hematopoietic defects. The abnormalities in leukocyte production are transplantable, indicating that the defect resides in the hematopoietic cells. These studies demonstrate a physiologic role for a HOX gene in blood cell differentiation, with the greatest apparent influence of HOXA9 at the level of the committed progenitor.

Asunto(s)

Médula Ósea/patología , Células Precursoras Eritroides/patología , Eliminación de Gen , Genes Homeobox , Hematopoyesis/genética , Linfocitos/patología , Animales , Linfocitos B/patología , Médula Ósea/metabolismo , Trasplante de Médula Ósea/patología , Diferenciación Celular/genética , Células Precursoras Eritroides/metabolismo , Femenino , Regulación de la Expresión Génica , Granulocitos , Humanos , Recuento de Linfocitos , Linfocitos/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Bazo/patología , Timo/patología

RESUMEN

Amongst the most important signal transduction molecules involved in regulating growth and differentiation are the protein tyrosine kinases (PTK). Since T cell development is a consequence of interactions between thymic stromal cells (TSC) and thymocytes, identification of the PTK in both compartments is required to dissect the mechanisms that control this process. Here we report a search for PTK in mouse TSC, using RT-PCR to survey the repertoire of PTK mRNAs expressed in a freshly isolated TSC preparation. We identified 10 different PTK cDNAs among the 216 cDNAs sequenced, and demonstrate that transcripts of three of those (ufo, fyn and fer) are widely expressed among a large panel of immortalized thymic epithelial cell lines (TEC) and in primary cultures of TSC. Of the other seven, none were expressed in established TEC lines but, instead, displayed distinct expression patterns in cell types likely to have contaminated the fresh TSC preparation, i.e., macrophages, B cells, T cells and fibroblasts. Among the three PTK expressed in TEC lines, only one, ufo, exhibited expression exclusively in cells of non-hemopoietic origin. Although expression of ufo (also known as tyro 7, axl or ark) is not thymic-specific, in that it is also expressed in cell types of mesodermal origin in other tissues, its presence in TEC suggests a role for ufo in differentiation of the TSC compartment. Consistent with this notion, high-level expression of this receptor PTK at the protein level could be documented in every TEC line investigated, as well as in fresh thymus tissue sections. These data provide the first example of a receptor PTK in TSC and open new approaches to study the regulation of TSC differentiation.

Asunto(s)

Expresión Génica/genética , Proteínas Tirosina Quinasas/biosíntesis , Proteínas Tirosina Quinasas/genética , Células del Estroma/metabolismo , Timo/citología , Timo/metabolismo , Secuencia de Aminoácidos , Animales , ADN Complementario/biosíntesis , Femenino , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Proteínas Oncogénicas/biosíntesis , Proteínas Oncogénicas/genética , Reacción en Cadena de la Polimerasa/métodos , Proteínas Proto-Oncogénicas , ADN Polimerasa Dirigida por ARN , Proteínas Tirosina Quinasas Receptoras/biosíntesis , Proteínas Tirosina Quinasas Receptoras/genética , Tirosina Quinasa del Receptor Axl

RESUMEN

Transformed murine fetal thymocyte cell lines were derived by incubating fetal thymic organ cultures with a v-myc/v-raf-containing retroviral construct in order to model developmental stages within the early triple negative (CD3-CD4-CD8-) thymocyte population. The resulting 10 cell lines had a lymphoid morphology, were all CD44+, CD90+, and were triple negative by surface antigen analysis. The cell lines, however, were distinguishable by differences in the expression of T cell-associated and T cell-specific genes. The CD3 genes were observed to be discoordinately expressed, in that CD3 gamma chain gene expression was detected in 2 cell lines in the absence of CD3 delta and epsilon expression. Expression of the CD3 gamma chain gene was observed in cell lines without the expression of other T cell-specific genes or T cell receptor rearrangement and may be one of the earliest T cell-specific genes to be expressed. The transcription factor Ikaros was expressed in all 10 cell lines, whereas the transcription factor TCF1 alpha was expressed only in the 2 most differentiated lines. In 8 cell lines, expression of partial TCR beta and/or TCR alpha transcripts was observed by Northern blot. In several lines, expression of rearranged TCR alpha transcripts in the absence of TCR beta transcripts was demonstrated; however, TCR beta DJ rearrangements were observed by Southern blot in all but 1 of these cell lines. Thus, these cell lines, ordered based on the general pattern of additive gene expression observed, may reflect various stages of triple-negative thymocyte differentiation and provide an in vitro mechanism to elucidate some of the molecular events involved in early thymocyte development.

Asunto(s)

Genes myc/inmunología , Linfocitos T/inmunología , Animales , Antígenos CD/análisis , Northern Blotting , Southern Blotting , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Línea Celular Transformada , Transformación Celular Viral/genética , Transformación Celular Viral/inmunología , Feto , Reordenamiento Génico de Linfocito T/inmunología , Inmunofenotipificación , Ratones , Técnicas de Cultivo de Órganos , Reacción en Cadena de la Polimerasa , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Timo/inmunología , Integración Viral/inmunología

RESUMEN

We recently described an mAb (MTS23) reactive with a membrane Ag expressed on a subset of thymic medullary stromal cells. This Ag is also constitutively expressed at high levels on peripheral B cells, macrophages, and thymic and splenic dendritic cells of C57BL/6 mice. A number of stromal cell lines derived from thymus and bone marrow also stain with MTS23, but thymocytes and peripheral T cells only weakly express the Ag detected by MTS23. Here we show that the molecule detected by MTS23 is a member of the Ly-6 family of phosphatidylinositol-anchored membrane proteins. Treatment of stromal cells with phosphatidylinositol-phospholipase C before staining completely abolished expression. Using transient expression of 293T cells and a cDNA library of a stromal cell line cloned into the pEF-BOS vector, a cDNA encoding the MTS23-target Ag was isolated. Partial sequencing and restriction enzyme mapping revealed that it represents the Ly-6A/E protein. While the physiologic significance of the presence of Ly-6 molecules on stromal cells is not clear, it has been known for some time that, at least in lymphocytes, cellular activation events can be induced upon Ly-6 engagement. We now demonstrate that Ly-6 also functions as a signal transduction molecule on stromal cells, in that granulocyte-macrophage CSF can be produced by a variety of stromal cell lines upon mAb-mediated cross-linking of Ly-6. Together with the dramatic up-regulation of Ly-6 expression on stromal cells upon IFN-gamma treatment, this is the first indication of a biologic function of an Ly-6 gene product on nonhemopoietic cells. The results suggest that Ly-6 may play a role in the cross-talk between lymphocyte precursors and stromal cells.

Asunto(s)

Antígenos Ly/metabolismo , Médula Ósea/inmunología , Timo/inmunología , Animales , Anticuerpos Monoclonales , Antígenos Ly/genética , Médula Ósea/metabolismo , Células de la Médula Ósea , Línea Celular , Clonación Molecular , Reactivos de Enlaces Cruzados , ADN Complementario/genética , Expresión Génica , Factor Estimulante de Colonias de Granulocitos y Macrófagos/biosíntesis , Ratones , Ratones Endogámicos C57BL , Transducción de Señal/inmunología , Timo/citología , Timo/metabolismo

RESUMEN

Two candidate genes for controlling thymocyte differentiation, T-cell factor-1 (Tcf-1) and lymphoid enhancer-binding factor (Lef-1), encode closely related DNA-binding HMG-box proteins. Their expression pattern is complex and largely overlapping during embryogenesis, yet restricted to lymphocytes postnatally. Here we generate two independent germline mutations in Tcf-1 and find that thymocyte development in (otherwise normal) mutant mice is blocked at the transition from the CD8+, immature single-positive to the CD4+/CD8+ double-positive stage. In contrast to wild-type mice, most of the immature single-positive cells in the mutants are not in the cell cycle and the number of immunocompetent T cells in peripheral lymphoid organs is reduced. We conclude that Tcf-1 controls an essential step in thymocyte differentiation.

Asunto(s)

Proteínas de Unión al ADN/fisiología , Proteínas de Homeodominio/fisiología , Linfocitos T/citología , Timo/citología , Factores de Transcripción/fisiología , Animales , Secuencia de Bases , Ciclo Celular , Diferenciación Celular , ADN , Proteínas de Unión al ADN/genética , Mutación de Línea Germinal , Factor Nuclear 1-alfa del Hepatocito , Inmunofenotipificación , Recuento de Linfocitos , Factor de Unión 1 al Potenciador Linfoide , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Factor 1 de Transcripción de Linfocitos T , Linfocitos T/inmunología , Factores de Transcripción/genética

RESUMEN

E12 and E47 are two helix-loop-helix transcription factors that arise by alternative splicing of the E2A gene. Both have been implicated in the regulation of immunoglobulin gene expression. We have now generated E2A (-/-) mice by gene targeting. E2A-null mutant mice fail to generate mature B cells. The arrest of B cell development occurs at an early stage, since no immunoglobulin DJ rearrangements can be detected in homozygous mutant mice. While immunoglobulin germline I mu RAG-1, mb-1, CD19, and lambda 5 transcripts are dramatically reduced in fetal livers of E2A (-/-) mice, B29 and mu degrees transcripts are present, but at lower levels. In addition, we show that Pax-5 transcripts are significantly reduced in fetal livers of E2A (-/-) mice. These data suggest a crucial role for E2A products as central regulators in early B cell differentiation.

Asunto(s)

Linfocitos B/fisiología , Proteínas de Unión al ADN/metabolismo , Genes de Inmunoglobulinas/genética , Proteínas de Homeodominio , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , Diferenciación Celular , Proteínas de Unión al ADN/genética , Reordenamiento Génico , Homocigoto , Cadenas lambda de Inmunoglobulina/genética , Tejido Linfoide/inmunología , Ratones , Ratones Mutantes , Datos de Secuencia Molecular , Proteínas/genética , ARN Mensajero/análisis , ARN Mensajero/genética , Factores de Transcripción TCF , Proteína 1 Similar al Factor de Transcripción 7 , Factores de Transcripción/genética

RESUMEN

T cell maturation results in part from direct cell-cell interactions between developing thymocytes and thymic stromal cells. Identification of the cell surface molecules involved in these interactions has been approached by production of mAbs reactive to thymic stromal cell surface Ags. A mAb against one such Ag, mouse thymic stroma (MTS) mAb MTS 23, stains a subset of thymic medullary epithelium by immunohistology. In addition, it was found to detect, by flow cytometry, an Ag constitutively expressed on peripheral B cells and macrophages as well as thymic and splenic dendritic cells. This Ag was also up-regulated on T cells and thymocytes within 24 to 48 h after activation. We then investigated whether the Ag identified by MTS 23 may represent a functional accessory molecule. MTS 23 was able to block up to 75% of T cell proliferation in soluble anti-CD3 and Ag-induced responses in a dose-dependent manner, but not under conditions in which no APCs were required. The molecule detected by this mAb has an apparent molecular mass of 120 kDa under reducing and nonreducing conditions. On the basis of these molecular properties and expression pattern, it is therefore postulated that MTS 23 may detect a novel accessory molecule important for T cell activation. Its expression on thymic epithelium is consistent with the notion that T cell development is not solely a consequence of unique molecular interactions, but also of signals arising from combinations of interactions involving molecules also expressed extrathymically.

Asunto(s)

Células Presentadoras de Antígenos/inmunología , Antígenos de Superficie/metabolismo , Subgrupos de Linfocitos T/inmunología , Timo/citología , Animales , Anticuerpos Monoclonales/inmunología , Antígenos de Superficie/química , Biomarcadores , Epitelio/inmunología , Citometría de Flujo , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Peso Molecular , Timo/inmunología

RESUMEN

BACKGROUND: Colon-specific antigen-p is a tumor-associated antigen present in approximately 60% of colorectal cancers. Preclinical studies have shown that the murine monoclonal antibody Mu-9 has excellent tumor-targeting abilities; therefore, clinical studies were initiated. METHODS: The immunoglobulin G and F(ab')2 were radiolabeled with 131I and administered to 13 and 12 patients, respectively, with advanced gastrointestinal cancer (colon, rectal, and pancreatic) for radioimmunodetection or radioimmunotherapy. RESULTS: Even in patients with highly elevated carcinoembryonic antigen levels, only one patient showed appreciable complexation of the labeled antibody, suggesting the epitope may not be highly expressed in the blood. Fifty percent of 131I-Mu-9 immunoglobulin G was cleared from the blood within 41 +/- 13 hours, while it took only 19 +/- 8 hours for the same amount of 131I-F(ab')2 to be cleared from the blood. Lesion detection in the abdomen, liver, and pelvis was greater than 90% for either the immunoglobulin G or F(ab')2. The dose absorbed by the normal organs, except the kidneys, was two- to threefold less for the F(ab')2 than for the whole immunoglobulin G. The dose to the kidneys was similar for both forms of immunoglobulin. The average tumor dose for 131I-Mu-9 immunoglobulin G was 13.9 +/- 11.0 cGy/mCi, and for 131I-F(ab')2 was 4.9 +/- 2.9. Tumor/red marrow dose ratios for the whole immunoglobulin G were 4.3 +/- 3.0, compared to 3.3 +/- 1.9 for the F(ab')2, suggesting the therapeutic window for the two forms of immunoglobulin may be similar. Eight of nine patients given the whole immunoglobulin G developed highly elevated levels of human anti-mouse antibody, whereas lower values were observed in five of seven patients given the F(ab')2. CONCLUSIONS: These initial results support the need for further evaluation of Mu-9 immunoglobulin G and F(ab')2 for targeting gastrointestinal cancer for radioimmunotherapy.

Asunto(s)

Anticuerpos Monoclonales/uso terapéutico , Antígenos de Neoplasias/inmunología , Neoplasias Gastrointestinales/terapia , Radioisótopos de Yodo/uso terapéutico , Adulto , Anciano , Animales , Anticuerpos Monoclonales/metabolismo , Formación de Anticuerpos , Biomarcadores de Tumor , Femenino , Semivida , Humanos , Fragmentos Fab de Inmunoglobulinas/inmunología , Inmunoglobulina G/inmunología , Radioisótopos de Yodo/farmacocinética , Masculino , Ratones/inmunología , Persona de Mediana Edad , Radioinmunoterapia , Dosificación Radioterapéutica , Distribución Tisular

RESUMEN

Utilizing flow cytometry, the expression of antigens recognized by six thymic stromal cell (TSC) reactive mAbs was investigated on fresh TSCs and TSC lines. It was found that some thymic epithelial cells and dendritic cells share antigenic phenotypes, and that most TSC reactive mAbs have a more extensive distribution than would have been predicted from immunohistology. While these findings illustrate the higher sensitivity of flow cytometric analysis, they more importantly emphasize the great complexity of TSC that direct T cell development. In order to identify the molecular parameters that define the various steps involved in T cell differentiation, TSC antigens (non-TCR/MHC/co-receptor) that are functional will have to be identified. This study represents the initial steps in characterizing such antigens.

Asunto(s)

Células del Estroma/inmunología , Timo/citología , Animales , Anticuerpos Monoclonales , Antígenos de Diferenciación/análisis , Células Dendríticas/inmunología , Femenino , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Bazo/citología , Timo/inmunología

RESUMEN

Radiation therapy has been shown to be the most effective prophylactic measure against heterotopic ossification (HO) in surgically repaired hip fractures. Current research is seeking the minimum effective dose of radiation. The authors present four case reports and a review of the literature on HO.

Asunto(s)

Fracturas de Cadera/cirugía , Osificación Heterotópica/prevención & control , Complicaciones Posoperatorias/prevención & control , Adulto , Femenino , Fracturas de Cadera/radioterapia , Humanos , Masculino , Persona de Mediana Edad , Osificación Heterotópica/radioterapia , Periodo Posoperatorio , Resultado del Tratamiento

Asunto(s)

Timo/citología , Animales , Humanos , Linfocitos T/inmunología , Timo/inmunología

RESUMEN

Activation of antigen specific T cells requires more than stimulation through the TCR-CD3 complex. A second or costimulatory signal is also required, and this second signal can be delivered by interactions between CD28 and B7, ligands expressed on T cells and antigen presenting cells respectively. We have examined the role of the CD28-B7 interaction in superantigen mediated T cell activation and intrathymic negative selection by blocking B7 molecules with a high affinity soluble ligand, CTLA4lg. In vitro T cell activation mediated by both virally encoded endogenous and exogenous bacterial superantigens was significantly blocked by the addition of CTL4Alg to cultures. However, intrathymic clonal deletion in vivo and in fetal thymic organ cultures was not inhibited by blocking B7 molecules. Therefore, although the CD28-B7 costimulation pathway is necessary for T cell activation, it does not appear to play a role in intrathymic clonal deletion.

Asunto(s)

Antígenos CD , Antígenos de Diferenciación de Linfocitos T , Antígenos de Superficie , Inmunoconjugados , Linfocitos T/inmunología , Abatacept , Animales , Células Presentadoras de Antígenos/inmunología , Antígenos de Diferenciación , Antígeno B7-1 , Unión Competitiva , Antígenos CD28 , Antígeno CTLA-4 , Células Clonales/citología , Células Clonales/inmunología , Activación de Linfocitos , Ratones , Ratones Endogámicos , Técnicas de Cultivo de Órganos , Transducción de Señal/inmunología , Linfocitos T/citología , Timo/citología , Timo/inmunología

RESUMEN

BACKGROUND: The authors previously reported that an anticarcinoembryonic antigen antibody against a carcinoembryonic antigen (CEA)-specific epitope is preferred for clinical investigations. They developed a second generation, CEA-specific murine monoclonal antibody (MoAb), MN-14 (IMMU-14), that has a tenfold higher affinity. This report summarizes the initial clinical experience with the new MoAb. METHODS: MN-14 immunoglobulin G (IgG) (0.5-6.0 mg) was labeled with radioactive iodine (I131) (5-80 mCi) and injected into 22 patients with cancer. External scintigraphy was used to determine targeting in patients with low and highly elevated plasma CEA. Quantitative external scintigraphy methods were used to determine organ and tumor clearance rates and absorbed radiation doses. Targeting data were correlated with several factors, including MoAb protein dose, plasma CEA, and relative tumor burden. RESULTS: Despite more than 80% complexation with plasma CEA of more than 500 ng/ml, all known tumor sites were disclosed by external scintigraphy. The overall sensitivity of tumor targeting on a lesion basis was 89%. The residence time in the blood was predicted by body weight (P = 0.05) and the log of plasma CEA (P = 0.043). The absorbed dose to the red marrow and total body could be predicted by the body weight of the patient, but no other factor contributed significantly to the clearance rate or absorbed dose to the organs. Individual tumors received an average dose of 9.3 +/- 6.4 cGy/mCi. The absorbed dose to the tumors was negatively correlated to the weight of the tumor, and the percent uptake in the tumor was positively correlated to the estimated total tumor burden. Patients injected with approximately 5 mg of MN-14 IgG were more likely to have anti-mouse antibodies (HAMA) develop than were patients who were injected with less MoAb. CONCLUSIONS: These results suggest that MN-14 targets tumors effectively, even in the presence of elevated circulating CEA. Additional studies are necessary to determine if an advantage for the higher affinity MN-14 MoAb, compared with the lower affinity NP-4 MoAb, can be appreciated clinically.

Asunto(s)

Antígeno Carcinoembrionario/inmunología , Radioisótopos de Yodo , Neoplasias/diagnóstico por imagen , Radioinmunodetección , Adulto , Anciano , Animales , Anticuerpos Antiidiotipos/análisis , Antígeno Carcinoembrionario/sangre , Estudios de Evaluación como Asunto , Femenino , Humanos , Inmunoglobulina G/inmunología , Masculino , Ratones , Persona de Mediana Edad , Tomografía Computarizada de Emisión de Fotón Único

RESUMEN

B7 expression appears much more extensive than previously recognized with anti-human B7 reagents on human leucocyte populations: it is extremely high on splenic and thymic DC, moderate on macrophages and activated B cells, and low on resting B cells. Additionally, B7 is entirely undetectable on any thymic epithelial cells belonging to a panel of transformed cell lines and T cells, but its expression on epithelial cells in situ is still under investigation. This expression pattern is consistent with the hierarchy of costimulatory signal activity among these cell types, with DC being the most effective, and epithelial cells (like other cells of non-hemopoietic origin) not at all. Future studies will investigate to which extent B7 is involved in clonal deletion, i.e., the selection process dependent on self-antigen presentation by DC and B cells.

Asunto(s)

Células Presentadoras de Antígenos/inmunología , Tolerancia Inmunológica , Cadenas beta de Integrinas , Subgrupos de Linfocitos T/inmunología , Timo/inmunología , Animales , Anticuerpos Monoclonales/inmunología , Antígenos de Neoplasias/inmunología , Moléculas de Adhesión Celular/inmunología , Humanos , Integrinas/inmunología , Activación de Linfocitos , Ratones , Modelos Biológicos , Timo/citología

RESUMEN

Sixteen patients with non-Hodgkin's lymphoma were infused with 6.2 to 58.2 mCi (0.2 to 3.9 mg) doses of radioactive iodine (131I)-labeled LL2 immunoglobulin G (IgG) or F(ab')2, in order to study antibody distribution, pharmacokinetics, dosimetry, toxicity, tumor targeting, and therapy. LL2 is a murine IgG2a monoclonal antibody (MAb) reactive with B cells and non-Hodgkin's B-cell lymphoma. In a series of five assessable therapy patients, doses as small as 30 mCi 131I-LL2 IgG or F(ab')2 resulted in tumor responses (two partial remissions, two mixed and minor responses, and one no response), while one patient receiving diagnostic doses as low as 6.2 mCi showed a partial remission for 1 year and a complete remission after a second low radiation dose. No acute toxicities were noted, and only myelotoxicity accompanied therapeutic doses, with grade IV marrow toxicity seen in three of seven patients receiving total doses of about 50 mCi. Dosimetry calculations showed spleen and tumor dose rules of about 4.6 cGy/mCi, which was three to four times the dose to other organs. Despite the administration of relatively low doses of LL2 (0.2 to 3.9 mg), 82% of 60 known extrasplenic lymphoma sites were imaged. Serum clearance showed an average distribution half-life (T1/2) of 2.1 hours and an elimination T1/2 of 32.0 hours. The average total-body clearance T1/2 was 43 to 45 hours. LL2's antigenic target does not appear to be shed in high amounts into the circulation. Three of eight patients having at least two injections showed a human antimouse antibody response. These patients may have been presensitized to animal protein. An interesting observation in this study was the marked drop in circulating B lymphocytes after the administration of radioiodinated LL2 or anticarcinoembryonic antigen MAbs, suggesting that this is a nonspecific radiation effect and not necessarily related to the binding of MAb to normal B cells.

Asunto(s)

Anticuerpos Monoclonales/uso terapéutico , Radioisótopos de Yodo/uso terapéutico , Linfoma de Células B/terapia , Adulto , Anciano , Anticuerpos Antiidiotipos/biosíntesis , Terapia Combinada , Femenino , Humanos , Fragmentos Fab de Inmunoglobulinas/uso terapéutico , Inmunoglobulina G/uso terapéutico , Linfoma de Células B/diagnóstico por imagen , Masculino , Persona de Mediana Edad , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Tomografía Computarizada de Emisión de Fotón Único , Tomografía Computarizada por Rayos X

Asunto(s)

Anticuerpos Monoclonales/uso terapéutico , Neoplasias/terapia , Animales , Humanos , Inmunoterapia , Ratones