Utility of quantitative flow cytometry immunophenotypic analysis of CD5 expression in small B-cell neoplasms.

[waldenström macroglobulinemia]

The value of assessing CD 5 expression in the differential diagnosis of small B-cell neoplasms is well established . Assessment is usually done qualitatively .To assess CD 5 expression levels by quantitative flow cytometry immunophenotyping and to determine possible differences among various small B-cell neoplasms .We performed 4 -color flow cytometry analysis on specimens of peripheral blood and bone marrow aspirate and quantified CD 5 expression in various small B-cell lymphomas and leukemias . We also assessed CD 5 levels in peripheral blood samples of healthy blood donors .Cases of chronic lymphocytic leukemia and mantle cell lymphoma had higher levels of CD 5 compared with control B cells (P < .001 ). Cases of marginal zone lymphoma and hairy cell leukemia had CD 5 levels similar to control B cells (P = .35 and P = .14 , respectively ), whereas cases of follicular lymphoma and lymphoplasmacytic lymphoma had significantly lower CD 5 levels than control B cells (P < .001 and P = .04 , respectively ). In B-cell neoplasms , a high level of CD 5 expression was correlated with a homogeneous pattern of positive events , whereas lower CD 5 levels were correlated with heterogeneous patterns of positive events .Using flow cytometric immunophenotypic analysis to quantify CD 5 levels can aid in diagnosis . CD 5 expression levels are higher in patients with chronic lymphocytic leukemia and mantle cell lymphoma , and expression is observed in a homogeneous pattern , as compared with other B-cell neoplasms that are either negative for CD 5 or express CD 5 at lower levels with a heterogeneous pattern . However , there is some overlap in CD 5 expression levels between a subset of atypical chronic lymphocytic leukemia and marginal zone lymphoma cases .