Use of Flow Cytometry to Evaluate the Immunophenotypic Profile of Patients with Chronic Lymphocytic Leukemia from Rio Grande Do Norte State, Brazil

BACKGROUND: Chronic lymphocytic leukemia (B-CLL) is a clonal proliferation of mature B lymphocytes characterized by indolent clinical course. This clonality is characterized biologically by low expression of surface immunoglobulin (sIg) and restriction to a single immunoglobulin light chain associated with high expression of CD5 antigen and positivity to B cell antigen lymphocytes such as CD19, CD20 and CD23 and negativity to FMC7. The immunological profile and morphological analysis of lymphoid cells are the main means for the differential diagnosis of B-CLL from other chronic lymphoproliferative diseases. OBJECTIVE: The aim of this study was to evaluate the expression pattern of a variety of membrane antigens in leukemic cells originating from patients with B-CLL. METHODS: Peripheral blood samples from 80 patients with B-CLL were analyzed by multiparametric flow cytometry and routine hematologic exams, using a panel of monoclonal antibodies (MoAb): CD45/CD14, CD3/CD19/CD45, CD4/CD8/CD3, CD20/CD5/CD3, CD3/CD16-56/CD45, CD2/CD7, FMC7/CD23, CD103/CD22/CD20, HLADR/CD38, CD10/CD19, CD1a, CD11b in addition to IgM/gD, kappa and lambda immunoglobulin light chains to detect surface immunoglobulin and clonal restriction for immunoglobulin light chains. The hematological data were obtained using a hematological analyzer and cytomorphological analysis in blood film stained with Leishman's stain.RESULTS: The study sample consisted of 45 men and 35 women, ages ranging from 55 to 84 years (mean 65 years). Complete white blood cell count ranged from 10.0 to 42.0 x 10⁹/L. (mean 50.0 x 10⁹/L) and lymphocyte count was greater than 5.0 x 10⁹/l in all cases. The neoplastic cells displayed B-CLL phenotype (CD5+/CD19+/CD20+/HLADR+/CD23+) in the vast majority of the cases, associated with failure to stain for T cell markers (CD1a, CD2, CD4, CD3, CD7, CD8), CD103, CD14 and FMC7. Leukemic cells of most patients also expressed low intensity of IgM and IgD, with clonal restricted kappa light chain in the majority of cases (59.7%). CONCLUSIONS: This investigation highlights the importance of immunophenotyping for correct diagnosis of chronic lymphoproliferative syndromes, and the MoAb panel used was sufficient for diagnostic confirmation of B-CLL.