Immunophenotypic characteristics of the blast crisis in chronic myeloid leukemia.

OBJECTIVE: To characterize the immunophenotype of blast crisis (BC) in Mexican patients with chronic myeloid leukemia (CML). MATERIAL AND METHODS: Mononuclear cells of 17 patients with CML in BC were immunophenotyped employing a panel of 18 monoclonal antibodies: CD5, CD10, CD14, CD22, and anti-HLA-DR used in all patients; CD2, CD15, CD19, CD34, and CD41 in 13 to 16 patients; and CD3, CD7, CD13, CD20, CD21, CD33, CD42b, and CD61 in less than 10 patients. RESULTS: Myeloid was the most frequent type (9/17 cases) followed by lymphoid (6/17) and hybrid or mixed lineage (2/17). Four of the myeloid BC expressed megakaryocyte/platelet associated antigens; 5 of 6 cases with lymphoid BC showed an early precursor B cell immunophenotype (HLA-DR+, CD10+), and the other was an uncommon case of lymphoid B/T transformation (CD19+, CD5+). The CD34 antigen was present in 6 out of 15 cases: 4 patients with lymphoid BC, 1 with myeloid transformation, and 1 with megakaryoblastic BC. CONCLUSIONS: Our findings are comparable to those found in the literature comprising 192 patients. The present study confirms the lineage heterogeneity of CML BC and suggests that extensive immunophenotyping may allow insight for a more precise recognition of normal and leukemic ontogenesis.