RESUMEN
Subunit immunogens containing tandemly repeated copies of T- and B-cell epitopes have been shown to be more immunogenic than the respective immunogen containing only a single copy of the sequence. It has been unclear, however, whether the increased immunogenicity of a tandemly repeated B-cell epitope necessarily results from increased helper T-cell responses to intrinsic T-cell epitopes in the tandemly repeated sequences, or to neodeterminant T-cell epitopes created at the junction of adjacent repeat sequences. We examined this question by comparing the immunogenicity in mice of two immunogens containing one or eight tandemly repeated copies of an HIV-1 V3 loop haptenic sequence. Our results show that the tandemly repeated haptenic sequence potentiates the immunogenicity of the protein construct, likely through the facilitation of enhanced B-cell interaction with the tandem repeat construct and the consequent elicitation of increased carrier protein-specific helper T-cell responses.
Asunto(s)
Proteínas Portadoras/inmunología , Proteínas gp160 de Envoltorio del VIH/inmunología , Haptenos/inmunología , ISCOMs/inmunología , Péptidos/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Secuencia de Aminoácidos , Animales , Linfocitos B/inmunología , Antígenos H-2/inmunología , Antígenos H-2/metabolismo , Anticuerpos Anti-VIH/biosíntesis , Infecciones por VIH/inmunología , Infecciones por VIH/prevención & control , VIH-1/química , VIH-1/inmunología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Datos de Secuencia Molecular , Secuencias Repetitivas de AminoácidoRESUMEN
Adenosine deaminase (ADA), a purine salvage pathway enzyme, appears to play a key role in normal lymphocyte growth, development, and differentiation. Three new purine nucleoside analogues, deoxycoformycin, fludarabine, and 2-chlorodeoxyadenosine, affect the normal function of the purine salvage pathway by inhibiting ADA or by acting as analogs of the ADA substrates. These agents show significant activity in the treatment of chronic B-cell leukemias and low-grade lymphomas. The pharmacology, mechanism of action, and clinical usefulness of these agents are discussed.
Asunto(s)
2-Cloroadenosina/análogos & derivados , Antineoplásicos/uso terapéutico , Desoxiadenosinas/uso terapéutico , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Pentostatina/uso terapéutico , Vidarabina/análogos & derivados , 2-Cloroadenosina/química , 2-Cloroadenosina/farmacología , 2-Cloroadenosina/uso terapéutico , Antineoplásicos/química , Antineoplásicos/farmacología , Cladribina , Ensayos Clínicos como Asunto , Desoxiadenosinas/química , Desoxiadenosinas/farmacología , Pentostatina/química , Pentostatina/farmacología , Vidarabina/química , Vidarabina/farmacología , Vidarabina/uso terapéuticoRESUMEN
Chronic lymphocytic leukemia (CLL) and hairy cell leukemia (HCL) are two common chronic lymphoproliferative disorders, each having characteristic clinical, morphologic, and immunologic features. Phenotypically, CD5 reactivity in CLL and CD11c (Leu-M5) reactivity in HCL have characterized these two leukemias among B-cell disorders. In this study, we report 14 cases of a novel chronic lymphoproliferative disorder characterized by lymphocytosis and CD11c expression, but morphologically similar to CLL. The patients' ages ranged from 46 to 81 years (median 62). Eleven had palpable splenomegaly, five with markedly enlarged spleens; only one patient had generalized lymphadenopathy. The white blood cell count ranged from 5.2 to 131.0 x 10(9)/L (median 20.8). The morphologic diagnosis in all cases was CLL, with the cells usually having abundant cytoplasm. No morphologic features, of hairy cells were evident; tartrate-resistant acid phosphatase cytochemistry was negative in all cases. Bone marrow biopsies were available in 8 of 14. Four showed focal nodular infiltrates and two had diffuse infiltrates similar to CLL; two showed only minimal interstitial involvement. All cases expressed multiple B-cell markers, and 12 of 14 had monoclonal surface immunoglobulin. The leukemic cells of all cases strongly expressed CD11c, while CD5 was expressed in 7 of 14; only 1 of the 14 cases expressed the lymph node homing receptor, Leu-8. This unique group of leukemias appears to represent the malignant transformation of lymphocytes arising from a stage of lymphocyte differentiation between that found in typical cases of CLL and that of HCL. CD11c is known to have an important function in cellular adhesion and may be important in determining the pattern of lymphocyte tissue distribution found in this group of patients.
Asunto(s)
Antígenos CD/análisis , Antígenos de Diferenciación/análisis , Linfocitos B/inmunología , Leucemia de Células Pilosas/inmunología , Leucemia Linfocítica Crónica de Células B/inmunología , Fosfatasa Ácida/análisis , Anciano , Anciano de 80 o más Años , Antineoplásicos/uso terapéutico , Linfocitos B/patología , Médula Ósea/patología , Antígenos CD11 , Antígenos CD5 , Femenino , Histocitoquímica , Humanos , Inmunofenotipificación , Leucemia de Células Pilosas/patología , Leucemia de Células Pilosas/terapia , Leucemia Linfocítica Crónica de Células B/patología , Leucemia Linfocítica Crónica de Células B/terapia , Leucocitosis , Masculino , Persona de Mediana Edad , Esplenomegalia , TrombocitopeniaRESUMEN
We have found a single 4p+ chromosomal abnormality, 46,XX, -4, +der(4)t(3;4)(q13.3;p16), in a patient with an unusual B cell leukemia of mature phenotype characterized by a high white cell count, tartrate-resistant acid phosphatase-positive malignant cells, splenic white pulp proliferation, and a serum IgM monoclonal gammopathy. The malignant cells were characterized by surface expression of CD19 (B4), CD20 (B1), IgM, IgD, kappa, and HLA-DR. They were weakly positive for CD21 (B2) and negative for CD25 (interleukin-2 receptor). The malignant cells also showed clonal rearrangement of the immunoglobulin heavy chain and kappa light chain genes. A cell line, designated HCLW-3B, was derived from unstimulated peripheral blood obtained during the leukemic phase and was found to contain the same 4p+ chromosomal abnormality as well as genomic sequences of the Epstein-Barr virus nuclear antigen. A somatic cell hybrid constructed from HCLW-3B containing the derivative chromosome 4 was used to confirm that chromosome 3q was the source of the translocated material. The availability of a cell line which is clonally derived from the patient's circulating leukemia cells should permit further characterization of this translocation at the molecular level.
Asunto(s)
Aberraciones Cromosómicas/genética , Cromosomas Humanos Par 4 , Leucemia de Células B/genética , Southern Blotting , Aberraciones Cromosómicas/patología , Bandeo Cromosómico , Trastornos de los Cromosomas , Sondas de ADN , ADN Viral/análisis , Femenino , Reordenamiento Génico de Linfocito B , Genes de Inmunoglobulinas , Herpesvirus Humano 4/genética , Humanos , Persona de Mediana Edad , Translocación Genética , Células Tumorales CultivadasRESUMEN
A kindred with an autosomal dominant form of chronic hemolytic anemia has been found to have a 40- to 70-fold elevation in erythrocyte adenosine deaminase (ADA) activity in association with depletion of red blood cell (RBC) ATP pools. ADA activities in B lymphoblasts, skin fibroblasts, and granulocytes were normal. There were no alterations in the kinetic properties of partially purified proband ADA. We have shown by Western blot analysis that the elevation in ADA activity is accompanied by a corresponding increase in the amount of immunoreactive ADA protein. Southern blot analysis of proband DNA ruled out gene amplification and revealed no gross insertions, deletions, or rearrangements in the ADA gene. Northern blot analysis demonstrated a marked increase in the amount of ADA mRNA in proband and sibling reticulocytes compared to high reticulocyte controls. ADA mRNA levels in B lymphoblasts from the proband, sibling, and GM558 cell line were normal. Cloning and sequencing of proband reticulocyte cDNA revealed normal ADA mRNA sequence. No polymorphisms were detected among the seven clones studied. RNase mapping of the 5'- and 3'-non-coding sequences confirmed the quantitative increase in reticulocyte ADA mRNA and verified that these regions were normal in length and sequence. Southern blot analysis of DNA from four affected and three unaffected family members revealed two restriction fragment length polymorphisms (RFLPs) which segregate with the ADA allele from the unaffected grandfather. Both RFLPs are present in the unaffected grandchild and absent in the affected grandchild. These findings are consistent with a cis- mutation within the ADA gene, but they do not rule out a trans- mutation affecting some non-ADA regulatory factor. We conclude that erythrocyte-specific ADA overproduction is associated with increased amounts of structurally normal ADA mRNA. This increase may result from either increased transcription of the ADA gene or altered post-transcriptional processing resulting in increased stability of the RNA transcript. Further elucidation of the defect should provide valuable insights into the normal tissue-specific regulation of the ADA gene and the mechanisms by which erythroid cells regulate gene expression during differentiation.