Immunophenotypic Study of Basophils by Multiparameter Flow Cytometry

Abstract

Abstract Context.—The immunophenotypic profile of basophils is not yet fully established, and the immunophenotypic changes in chronic myelogenous leukemia are not fully characterized. Objective.—To establish a comprehensive immunophenotypic spectrum of normal basophils and to assess the range of immunophenotypic aberrations of basophils in chronic myelogenous leukemia. Design.—Using 4-color flow cytometry, we compared the immunophenotypic profile of basophils in peripheral blood or bone marrow samples from 20 patients with no evidence of neoplasia to basophils from 15 patients with chronic myelogenous leukemia. Results.—Basophils in control cases were all positive for CD9, CD13, CD22, CD25 (dim), CD33, CD36, CD38 (bright), CD45 (dimmer than lymphocytes and brighter than myeloblasts), and CD123 (bright), and were negative for CD19, CD34, CD64, CD117, and HLA-DR. Basophils in all chronic myelogenous leukemia patients possessed 1 to 5 immunophenotypic aberrancies. The most common aberrancies were underexpression of CD38, followed by aberrant expression of CD64 and underexpression of CD123. CD34 and CD117 were present in cases with basophilic precursors. Myeloblasts showed a distinct immunophenotypic profile, as they typically expressed CD34 and CD117, showed dimmer expression (compared with basophils) of CD38, CD45, and CD123, and lacked expression of CD22. Conclusions.—Flow cytometric immunophenotyping can identify immunophenotypic aberrations of basophils in chronic myelogenous leukemia, and discriminate basophils from myeloblasts.