IMMUNOHISTOLOGIC STUDY OF BONE-MARROW INVOLVEMENT IN B-CHRONIC LYMPHOCYTIC-LEUKEMIA

Abstract

Bone marrow trephine biopsies from 17 patients with B-chronic lymphocytic leukemia (B-CLL) were studied by immunohistologic techniques to investigate the cellular phenotypes of neoplastic (B-lymphoid) and reactive (T-lymphoid) infiltrates. For this purpose, several heteroantisera and monoclonal antibodies against human Ig isotypes, HLA-DR antigens and T-cell subpopulations were used in immunofluorescence. Findings were analyzed in relation to the histologic pattern of involvement and to the immunologic data of cell suspensions from peripheral blood. In all cases, the dominant lymphoid population within the bone marrow infiltrates showed identical phenotypic characteristics of B-CLL cells from the blood (HLA-DR+, .mu.+, most frequently .delta.+, .kappa.+ or .lambda.+, and weakly RFA-1+). Infiltration by these malignant B cells was diffuse in 5 cases and nodular plus interstitial in 12. The number of T cells (UCHT1+, RFA-1+, .mu.-) was variable (5-25%) in the different samples but the values were high when compared to the proportion of T cells in normal bone marrow and in the blood of most patients studied. A clear predominance of T cells exhibiting the inducer phenotype (Leu-3+) was observed in all bone marrow samples, which is in contrast with the findings from peripheral blood, where T cells with the suppressor/cytotoxic phenotype (Leu-2+) were dominant. Data suggest a different blood and tissue distribution of inducer and suppressor/cytotoxic cells in B-CLL, which may have important pathophysiologic significance.