RESUMEN
We previously reported that the distribution of the cells in normal bone marrow is fractal and self-similar. The purpose of this study was to determine whether the same is true in metastatic tumors. Thirty-two bone marrow biopsy sections (3 to 5 microm thick) of 28 patients were used to measure the fractal dimensions of the metastatic tumor cells' distribution. Microscopic images were obtained and were used for the fractal measurements. In the two-dimensional images, the fractal dimensions were 1.98 +/- 0.02 (95% +/- 5% cellularity), suggesting a compact nonfractal structure. The dimensions, however, were 1.72 +/- 0.1 (56% +/- 11% cellularity) for the normal components, with a P-value of <.0001 that is in agreement with our previous study. These results suggest that loss of the fractal structure in the metastatic lesions may be attributable to loss or suppression of the regulatory mechanisms maintaining the fractal morphogenesis of the bone marrow. This report provides a novel objective approach in the study of pathophysiology of the bone marrow disorders.
Asunto(s)
Neoplasias de la Médula Ósea/patología , Neoplasias de la Médula Ósea/secundario , Médula Ósea/patología , Adolescente , Adulto , Anciano , Médula Ósea/ultraestructura , Neoplasias de la Médula Ósea/ultraestructura , Niño , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Microscopía por Video , Persona de Mediana EdadRESUMEN
Two cases of mantle cell lymphoma with a unique CD8+ phenotype are reported. Both patients had disease that was resistant to therapy; one patient had the blastic variant of mantle cell lymphoma. Flow cytometric analysis of bone marrow and cerebrospinal fluid samples revealed a phenotype consistent with mantle cell lymphoma, with the additional finding of CD8 positivity in 40% or more of the tumor cells in both cases. This is the first description of such a finding, and CD8+ mantle cell lymphoma may represent a unique type of B-cell neoplasia. Our findings may be important in the prediction of therapeutic response or in the detection of residual disease after therapy.
Asunto(s)
Antígenos CD8/análisis , Linfoma no Hodgkin/inmunología , Antígenos CD20/análisis , Células de la Médula Ósea/inmunología , Complejo CD3/análisis , Antígenos CD5/análisis , Femenino , Citometría de Flujo , Fluoresceína-5-Isotiocianato , Colorantes Fluorescentes , Humanos , Inmunofenotipificación , Linfoma no Hodgkin/líquido cefalorraquídeo , Masculino , Persona de Mediana Edad , Receptores de IgE/análisisRESUMEN
Using a human melanoma/Scid xenograft model with the C8161, M24-met, LD-1 and other human melanoma lines to investigate spontaneous metastasis, we made the observation of marked splenomegaly (up to five times normal weight and size) in only those xenografts exhibiting high degrees of spontaneous metastasis. Evaluation of this revealed the cause to be massive myelopoiesis due to ectopic granulocyte/ colony-stimulating factor (G-CSF) production by the melanoma cells. Because of these observations linking G-CSF expression with metastasis of human melanoma, we decided to investigate the mechanism of this ectopic production. No gross amplification or rearrangement of the G-CSF gene could be detected as the basis for the increased transcriptional activity in any of these lines. Human-human somatic cell hybridization studies carried out between the metastatic C8161 and several different nonmetastatic non-G-CSF-expressing lines revealed, in addition to metastatic dominance, 3- to 10-fold enhancement of G-CSF transcription and expression in the fusions compared with C8161 itself. The suggestion of a trans-dominant mechanism was further supported by transfection studies with a human G-CSF promoter-CAT-reporter construct, which revealed 3- to 5-fold increased reporter activity in only those melanoma lines and hybrids expressing G-CSF. Furthermore, no obvious autocrine or paracrine effects of this ectopic G-CSF expression on the melanoma lines' growth or metastasis were apparent, as all of the G-CSF-expressing lines lacked the G-CSF receptor and injections of purified recombinant G-CSF exerted no stimulatory effects on their tumorigenicity, latency, growth, or metastasis in Scid mice. Thus, we advance the hypothesis that G-CSF expression is serving as a marker of a more generalized trans-dominant pathway linked to tumor progression and metastasis. This hypothesis has direct relevance to many human cancers where ectopic hormone or growth factor production occurs with no obvious autocrine or paracrine benefit to the tumor.
Asunto(s)
Factor Estimulante de Colonias de Granulocitos/genética , Melanoma/metabolismo , Melanoma/secundario , Neoplasias Cutáneas/metabolismo , Activación Transcripcional , Animales , Secuencia de Bases , Células Clonales , Progresión de la Enfermedad , Femenino , Genes Reporteros , Humanos , Células Híbridas , Inmunohistoquímica , Melanoma/genética , Ratones , Ratones SCID , Trasplante de Neoplasias , Neoplasias Cutáneas/genética , Neoplasias Cutáneas/patología , Bazo/patología , Esplenomegalia , Células Tumorales CultivadasRESUMEN
Bone marrow (BM) provides a particular spatial organization that allows interaction between its various components. Characterization of the spatial patterns in the BM and understanding the mechanisms that give rise to them may play a role in better understanding of the BM pathologic processes. Morphometric analyses were performed in BM biopsy samples from 30 patients (16 men and 14 women) with an average age of 46 years, ranging from 17 to 77 years. The biopsies were obtained during the course of patient care to rule out BM involvement in a variety of hematologic disorders before or after therapy. Three different, but structurally interrelated, parameters were measured: (A) cellular area, (B) nuclear area, and (C) cell numbers. All three methods, in all cases, showed that the spatial structure of the BM is fractal. The average values of the fractal dimensions (Df) were 1.7 +/- 0.08, 1.64 +/- 0.1, and 1.69 +/- 0.04 for categories A, B, and C, respectively. The overall value of Df for the cellularity in the range of 40% to 60% was about 1.67 +/- 0.09. Fractal dimensions of 1.6 to 1.7 represent configurations that correspond to two-dimensional diffusion limited aggregation structures, suggesting that the structural configuration of hematopoietic cells is dependent on the diffusion of regulatory cytokines in the BM.
Asunto(s)
Médula Ósea/crecimiento & desarrollo , Fractales , Adolescente , Adulto , Anciano , Biopsia , Médula Ósea/patología , Enfermedades de la Médula Ósea/patología , Recuento de Células , Núcleo Celular/ultraestructura , Tamaño de la Célula , Difusión , Femenino , Factores de Crecimiento de Célula Hematopoyética/metabolismo , Células Madre Hematopoyéticas/ultraestructura , Humanos , Masculino , Persona de Mediana Edad , MorfogénesisRESUMEN
Few salvage treatments are successful for patients with relapsed acute myelogenous leukemia after a short first remission, multiple relapses, or for patients with disease refractory to initial induction chemotherapy. To improve the results of salvage therapy we studied the efficacy and toxicity of a combination of G-CSF (5 mu tg/kg IV q day) used as a priming agent followed by continued exposure to G-CSF and high-dose cyatarabine (2 gm/m(2) IV q 12 hours x 12 doses) in fifteen adult patients with relapsed or refractory acute myelogenous leukemia. Nine of fourteen (64%; 95% confidence interval 35 to 87%) achieved complete remission, four failed to enter remission and one died of multiorgan system failure after progressive leukemia cutis despite chemotherapy-induced bone marrow aplasia. Median disease-free survival is 148 days and median survival from study entry for responding patient is 174 days. Three patients who achieved complete remission subsequently relapsed with a median time to relapse of 147 days. Median time to granulocyte >0.5 x 10(9)/L was 22 days (19 to 34 days) and the median time to platelet recovery >20 x 10(9)/L was 30 days (23 to 214 days). Although gastrointestinal toxicity was common, no patient developed severe cardiac, hepatic, pulmonary, or neurologic complications. An elevation in the percent of bone marrow blasts in S-phase after 48 hours of treatment with G-CSF was identified in 7 of 12 evaluable patients. These results demonstrate that the combination of G-CSF and high-dose cytarabine may be used as an effective salvage treatment for patients with resistant acute myelogenous leukemia.
Asunto(s)
Antimetabolitos Antineoplásicos/uso terapéutico , Citarabina/uso terapéutico , Factor Estimulante de Colonias de Granulocitos/uso terapéutico , Factores Inmunológicos/uso terapéutico , Leucemia Mieloide/terapia , Enfermedad Aguda , Adolescente , Adulto , Anciano , Antimetabolitos Antineoplásicos/administración & dosificación , Antimetabolitos Antineoplásicos/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Terapia Combinada , Citarabina/administración & dosificación , Citarabina/efectos adversos , Supervivencia sin Enfermedad , Femenino , Filgrastim , Enfermedades Gastrointestinales/inducido químicamente , Factor Estimulante de Colonias de Granulocitos/administración & dosificación , Factor Estimulante de Colonias de Granulocitos/efectos adversos , Humanos , Factores Inmunológicos/administración & dosificación , Factores Inmunológicos/efectos adversos , Leucemia Mieloide/tratamiento farmacológico , Leucemia Mieloide/mortalidad , Masculino , Persona de Mediana Edad , Proteínas Recombinantes , Inducción de Remisión , Terapia Recuperativa , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
It has been estimated that 1 to 3% of the general population may be ataxia-telangiectasia (A-T) heterozygotes and hypersensitive to conventional doses of radiation. We attempted to identify heterozygotes by evaluating the proportion of cells in various phases of the cell cycle in response to irradiation. This was accomplished by using flow cytometry to study lymphoblastoid cell lines (LCLs) from 14 A-T homozygotes, 17 genotypic A-T heterozygotes, and 18 normal individuals, including 10 genotypic normals. The LCLs were exposed to 2-gRay radiation and were analyzed after 24 hr along with nonirradiated controls. The difference between the percentage of cells in G2/M with and without irradiation after 24 hr ranged, respectively, from: 12.0 to 31.5% (mean = 18.7 +/- 5.5) for A-T homozygotes; 6.7 to 19.3% (mean = 12.5 +/- 3.8) for A-T heterozygotes; and -1.5 to 12.4% (mean = 6.4 +/- 3.2) for normals. A cut-off region of 9.6 to 13.2% defined by one standard deviation above the mean for normals and one standard deviation below the mean for A-T homozygotes served as the grey zone between normals and A-T heterozygotes or homozygotes. Two of the 18 normals overlapped with the grey zone. Four of 17 heterozygotes were within the normal range; seven fell within the grey zone. This may reflect nongenetic variables, such as the status of the LCLs at the time of testing. Flow cytometry cell-cycle analysis on irradiated LCLs is a useful adjunctive test for establishing a diagnosis of A-T in questionable cases.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Ataxia Telangiectasia/genética , Ciclo Celular/genética , Citometría de Flujo/métodos , Subgrupos Linfocitarios/efectos de la radiación , Ataxia Telangiectasia/patología , Ciclo Celular/efectos de la radiación , Línea Celular , Fase G2/genética , Rayos gamma , Humanos , Mitosis/genéticaRESUMEN
Like other normal diploid mammalian cells, human T-lymphocytes display a limited in vitro lifespan. Long-term cultures of normal adult peripheral blood T cells, activated in vitro and passaged in the presence of interleukin-2 undergo 23 +/- 7 cumulative population doublings. Cell cycle analysis revealed that in senescent T cell cultures, restimulation with the original antigen resulted in 16-22% of the cells entering S phase, compared to 60% entering cycle in young cultures. In addition, within 1 week of restimulation, the senescent cultures do not increase in cell number, but 93% of the cells return to the G1/G0 DNA content, a proportion typically seen in quiescent (nonrestimulated) cultures. Coculture of early- and late-passage cells at two different ratios excluded a putative inhibitory factor produced by the old cells and similarly eliminated a possible stimulatory product in early cultures. Flow cytometry measure of forward angle light scatter revealed no difference in cell size between early- and late-passage cells, in contrast to the findings with senescent fibroblasts. Thus, while increasing cell size may contribute to the senescent phenotype of fibroblast cultures, it is not a factor in the senescence of human T-lymphocytes, and it is therefore doubtful that alterations in cell size are fundamental to in vitro cellular aging.
Asunto(s)
Senescencia Celular , Linfocitos T/fisiología , Ciclo Celular , División Celular , Tamaño de la Célula , Células Cultivadas/fisiología , ADN/análisis , Fibroblastos , Humanos , Técnicas In VitroRESUMEN
Normal human T lymphocytes, activated in vitro and cultured in the continuous presence of the growth factor interleukin 2 (IL2), have a limited proliferative potential. Senescent T cell cultures will not proliferate, even if restimulated by the original allogeneic stimulator cells. However, we have now observed that such restimulation induces an increase in the percentage of cells expressing the 55 kDa chain of the IL2 receptor (IL2R alpha, CD25) without any associated increase in cell number. A younger culture, which showed a comparable increase in CD25, underwent two population doublings in the same time period after restimulation. The senescent cultures, (primarily of the CD8+, cytotoxic/suppressor, phenotype), were also found to be highly potent and specific effector cells in a 51chromium release assay for cytolytic activity. Furthermore, senescent cultures maintain the surface phenotype of memory T cells. These findings demonstrate that while senescent T cells are unable to proliferate in response to restimulation or to IL2, they are able to recognize the foreign stimulator cells and to initiate an otherwise normal T cell response. Our results lend support to the hypothesis that in vitro senescence is not associated with a generalized decline in functional activity in a differentiated cell type, but with a specific event which limits cell division. Thus, the long term T lymphocyte culture system will be useful for studying the mechanism by which proliferation is blocked in these, apparently, post-mitotic cells.
Asunto(s)
Linfocitos T/citología , Linfocitos T/inmunología , Antígenos de Diferenciación de Linfocitos T , Diferenciación Celular , División Celular , Células Cultivadas , Senescencia Celular/inmunología , Citotoxicidad Inmunológica , Humanos , Memoria Inmunológica , Técnicas In Vitro , Isoantígenos , Activación de Linfocitos , Fenotipo , Receptores de Interleucina-2/metabolismoRESUMEN
We describe a unique case of chronic lymphocytic leukemia (CLL) in a patient who presented with bitemporal hemianopsia, adrenal insufficiency, and gonadotrophin deficiency. Studies revealed an enhancing intrasellar mass with suprasellar extension and displacement of the optic chiasm. Peripheral blood and cerebrospinal fluid (CSF) studies disclosed a monoclonal IgM kappa expressing B-cell CLL. Biopsy of the pituitary mass revealed dense infiltration of the pituitary gland by leukemic cells. This is, to our knowledge, the first reported case of CLL presenting as a pituitary mass lesion.
Asunto(s)
Leucemia Linfocítica Crónica de Células B/patología , Neoplasias Hipofisarias/patología , Encéfalo/diagnóstico por imagen , Femenino , Humanos , Leucemia Linfocítica Crónica de Células B/diagnóstico , Leucemia Linfocítica Crónica de Células B/diagnóstico por imagen , Hígado/diagnóstico por imagen , Persona de Mediana Edad , Quiasma Óptico/patología , Neoplasias Hipofisarias/diagnóstico por imagen , Cintigrafía , Bazo/diagnóstico por imagen , Tomografía Computarizada por Rayos XAsunto(s)
Autoanticuerpos/análisis , Lupus Eritematoso Sistémico/inmunología , Anticuerpos Antinucleares/análisis , Anticuerpos Antifosfolípidos/análisis , Humanos , Leucemia Mieloide Aguda/inmunología , Proteínas Nucleares/inmunología , Leucemia-Linfoma Linfoblástico de Células Precursoras/inmunología , Antígeno Nuclear de Célula en ProliferaciónRESUMEN
We studied 43 consecutive cases of acute leukemia for evidence of hybrid leukemia including biphenotypic or bilineal involvement. Twenty-two were initially diagnosed as acute lymphoblastic leukemia (ALL) and 21 as acute myelogenous leukemia (AML). Techniques included morphology, cytochemistry, immune phenotyping and cytogenetics. Thirty-one cases seemed restricted to one lineage. Twelve cases showed involvement of both lymphoid and myeloid cells. Dual staining immune phenotyping showed coexpression of diverse lineage markers. These data indicate a considerable proportion of unselected cases of acute leukemia are hybrid leukemias. These data are consistent with the notion that transformation frequently occurs in a stem or progenitor cell.
Asunto(s)
Transformación Celular Neoplásica/patología , Leucemia/patología , Enfermedad Aguda , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Aberraciones Cromosómicas , Femenino , Células Madre Hematopoyéticas/patología , Humanos , Inmunofenotipificación , Leucemia/genética , Leucemia/inmunología , Leucemia Mieloide Aguda/patología , Masculino , Persona de Mediana Edad , Células Madre Neoplásicas/patología , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologíaRESUMEN
Most cases of acute leukemia with deletions of chromosome 5q (5q-) are acute myelogenous leukemia. 5q- in acute lymphoid leukemia is rare. We studied a case of acute leukemia with 5q- using morphologic, cytochemical, immune and molecular techniques. Morphologic and cytochemical techniques were consistent with ALL (FAB L-2, PAS+, MPO-, ASD-). TdT was present. Immune studies suggested a T-cell phenotype (CD5+, CD7+); however, there was no rearrangement of the T beta-cell receptor gene. Surprisingly, the leukemia cells also expressed the CD13 myeloid antigen. Dual staining analysis showed co-expression of lymphoid and myeloid antigens on most cells. Based on these data and a review of previous reports we suggest that acute leukemia associated with the 5q- abnormality can occur in an immature stem cell resulting in a hybrid leukemia.
Asunto(s)
Aberraciones Cromosómicas , Deleción Cromosómica , Trastornos de los Cromosomas , Cromosomas Humanos Par 5 , Leucemia Mieloide Aguda/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Adulto , Antígenos CD/análisis , Médula Ósea/patología , Femenino , Humanos , Cariotipificación , Leucemia Mieloide Aguda/clasificación , Leucemia Mieloide Aguda/inmunología , Leucemia Mieloide Aguda/patología , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/clasificación , Leucemia-Linfoma Linfoblástico de Células Precursoras/inmunología , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Receptores de Antígenos de Linfocitos T/genética , Linfocitos T/inmunologíaRESUMEN
Translocations between chromosomes 8 and 21, t(8;21)(q22;q22), occur most commonly in acute myelogenous leukemia (AML) of the M2 FAB type. We studied two cases of acute leukemia with t(8;21) by immune phenotyping and IgH and T-cell receptor beta chain gene rearrangement analyses. These cases had increased blasts in bone marrow (greater than 50%). Auer rods, and evidence of granulocyte maturation. Blasts from both cases expressed CD19(B4), a B-cell antigen, as well as myeloid antigens including CD13(My7) and CD33(My9). HLA-DR, CD34, and TdT were also strongly positive. IgH or TCR beta gene rearrangements were not detected. We suggest that some cases of acute leukemia with t(8;21) may be hybrid leukemias with transformation in a multipotent stem cell.
Asunto(s)
Cromosomas Humanos Par 18 , Cromosomas Humanos Par 21 , Leucemia Mieloide Aguda/genética , Translocación Genética , Adulto , Antígenos CD/análisis , Southern Blotting , Reordenamiento Génico de la Cadena beta de los Receptores de Antígenos de los Linfocitos T , Humanos , Inmunofenotipificación , Cariotipificación , Leucemia Mieloide Aguda/inmunología , Masculino , Persona de Mediana EdadAsunto(s)
Leucemia/diagnóstico , Linfoma/diagnóstico , Anticuerpos Monoclonales , Biomarcadores de Tumor , Citogenética , ADN de Neoplasias/análisis , ADN de Neoplasias/genética , Humanos , Leucemia/clasificación , Leucemia/genética , Linfoma/clasificación , Linfoma/genética , Oncogenes , Coloración y EtiquetadoRESUMEN
The morphologic changes in the bone marrow of eight patients with refractory aplastic anemia who received 4 or more weeks of granulocyte macrophage-colony-stimulating factor (GM-CSF) are described. All eight patients demonstrated a continuous rise in the absolute number of neutrophils, eosinophils, and monocytes over the first four weeks of therapy. Bone marrow examination revealed a progressive increase in bone marrow cellularity in all patients except one. An increase in myeloid: erythroid ratio was seen with progressive maturation of granulocytic cells. Neutrophilic and eosinophilic myelocytes were the most prominent cells. The percentage of myeloblasts and promyelocytes did not increase significantly, and the proportions of postmitotic granulocytic cells did not change either. No significant morphologic changes were noted in the basophilic, erythroid, and megakaryocytic series. The most prominent topographic observation in the bone marrow during GM-CSF therapy was the frequent clustering of myeloid cells close to the bone trabeculae. The periosteal localization of myeloid precursors may reflect a higher concentration of stem cells and/or stromal cells in the bone marrow adjacent to the bone trabeculae or a higher concentration of growth factors. Careful morphologic examination of bone marrow in CSF clinical trials will provide useful information regarding the in vivo effects of these growth factors, and will aid in the development of a rational approach to combining them for therapy.
Asunto(s)
Anemia Aplásica/tratamiento farmacológico , Médula Ósea/patología , Factores Estimulantes de Colonias/uso terapéutico , Sustancias de Crecimiento/uso terapéutico , Anemia Aplásica/sangre , Anemia Aplásica/patología , Eosinófilos/efectos de los fármacos , Eosinófilos/patología , Factor Estimulante de Colonias de Granulocitos y Macrófagos , Humanos , Recuento de Leucocitos , Neutrófilos/efectos de los fármacos , Neutrófilos/patología , Proteínas Recombinantes/uso terapéuticoRESUMEN
Molecular pathology, defined broadly as the use of nucleic acid probes to diagnose and study disease, is an emerging discipline of growing importance and promise. Utilizing the principles of nucleotide base-pairing for specific hybridization between a DNA or RNA probe and its complementary target sequence, molecular diagnostic techniques are finding ever-increasing applications across the entire spectrum of human disease. These include infectious diseases (using DNA probes for viruses, bacteria, and parasites), neoplastic diseases (through detection of gene rearrangements, tissue-specific gene transcription, and oncogene activation), hereditary diseases (by screening for specific mutated genes or linked DNA polymorphisms), and the differentiation of individuals from one another by "DNA fingerprinting" (for purposes of donor recipient identification in transplants, paternity testing, or forensic investigations). This review surveys the current applications in each of these areas, along with the most important techniques now being used: Southern blotting, in situ hybridization, and the polymerase chain reaction. Finally, the impact of these powerful new methodologies on the entire field of diagnostic pathology is discussed.
Asunto(s)
Sondas Moleculares , Patología/métodos , Humanos , Técnicas de Sonda Molecular , Hibridación de Ácido Nucleico , Patología/tendencias , Reacción en Cadena de la PolimerasaRESUMEN
Proliferation of large granular lymphocytes may be associated with neutropenia and, less frequently, thrombocytopenia. In this report, we describe a patient with severe aplastic anemia in the setting of a proliferation of cells with natural killer (NK) phenotype. We demonstrated evolution to acute lymphoblastic leukemia by cells of identical phenotype.
Asunto(s)
Anemia Aplásica/inmunología , Células Asesinas Naturales/patología , Leucemia-Linfoma Linfoblástico de Células Precursoras/inmunología , Anemia Aplásica/sangre , Anemia Aplásica/patología , División Celular , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangre , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologíaRESUMEN
Established lymphoblastoid cell lines have provided a valuable reference source for studying neoplastic lymphoproliferative disorders in humans. However, two major problems are associated with the establishment and growth of these cell lines: (a) the established cell line may not represent the original neoplastic clone, and (b) contamination of the established cell line with the other cell lines may occur. Lymphoblastoid cell lines "W" and "SP5" were established from splenectomy specimens of two patients with hairy cell leukemia. Both cell lines displayed B cell characteristics by immunophenotypic and Ig gene rearrangement studies. The banding patterns of the rearranged Ig genes (heavy and light chains) in the W cell line were different and in the SP5 cell line were identical with the corresponding untransformed splenic cell lines, indicating that cell line SP5 did and cell line W did not represent the original neoplastic clone. Continuous cultures of some of the subclones derived from cell line W and SP5 led to the growth of the cell lines W15T, W17T, and SP5T which all demonstrated T cell features based on immunophenotypic and T cell receptor rearrangement studies. However, the T cell receptor alpha and beta rearranged bands as well as bands generated by hybridization with highly polymorphic DNA probes p YNH24 and 0-3315-32 in these three lines and a human T cell leukemia line (CEM), were identical indicating that W15T, W17T and SP5T cell lines were contaminated with CEM. Studies of gene establishment patterns and DNA polymorphisms by Southern blotting are effective methods to establish clonal identity and to rule out cellular contamination in lymphoblastoid cell lines.