title: Coexpression of T- and B-markers in a lymphoproliferative disorder.
abstract: An atypical case of lymphoproliferative disorder in which T- and B-cell antigens were coexpressed in the neoplastic cells is described. The disease was characterised by hepatosplenomegaly, lymphadenopathy, a low WBC (5 X 10(9)/l) and bone marrow infiltration. The predominant cell population (greater than 70%) comprised lymphoid cells with a range of nuclear irregularities and included some blast cells. 90% of the peripheral blood lymphocytes showed a mature T-helper phenotype (E+, T11+, T3+, T4+, T8-, T6-, TdT-) with coexpression of the specific B-markers B1 and FMC7, in 90% and 50% of cells, respectively. HLA-DR antigens were present in 55% of cells while surface and cytoplasmic immunoglobulins (Ig) were detected in less than 10% of cells. Molecular investigations with appropriate probes showed evidence of T-cell receptor gene rearrangement but no rearrangement for the genes of the Ig-heavy and -light chains. Cytogenetic studies revealed a translocation t(10;19) (p12; q13) in all the metaphases analyzed. This case demonstrates that the study of neoplastic cells with a battery of monoclonal antibodies may disclose the existence of a hitherto unrecognised lymphoid cell population with atypical expression of B- and T-cell antigens. On the other hand, the presence of T-cell receptor gene rearrangement indicates that this is a T-cell disorder with the aberrant co-expression of specific B-cell markers.
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal; D000941:Antigens / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology* / Q000648:ultrastructure; D002879:Chromosomes, Human, Pair 10; D002888:Chromosomes, Human, Pair 19; D005260:Female; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D007621:Karyotyping; D007938:Leukemia / Q000235:genetics / Q000276:immunology*; D011947:Receptors, Antigen, B-Cell / Q000032:analysis; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology* / Q000648:ultrastructure; D014178:Translocation, Genetic
chemical_list: D000911:Antibodies, Monoclonal; D000941:Antigens; D006684:HLA-DR Antigens; D007136:Immunoglobulins; D011947:Receptors, Antigen, B-Cell