B-CELL PROLYMPHOCYTIC LEUKEMIA EXPRESSING CD13 ANTIGEN

Although the expression of myeloid-associated antigen CD13 has been re ported in aggressive B-cell chronic lymphocytic leukemia, its expressi on in other mature B-cell neoplasms appears to be rare. We report a 74 -year-old female with B-cell prolymphocytic leukemia (B-PLL) expressin g CD13 antigen. On admission, splenomegaly was noted. Hematological ex amination revealed at platelet count of 90 x 10(9/1) and a white cell count of 68 x 10(9/1) with 73% PLL cells. The hemoglobin concentration was 10.6 g/dl. A bone marrow aspirate showed a normocellular marrow w ith 64% PLL cells. Surface marker analysis of the PLL cells was positi ve for CD11b, CD13, CD19, CD20, CD24, HLA-DR, FMC7, mu and lambda. Sim ultaneous expression of CD13 and CD19 antigen was confirmed by dual co lor flow cytometry. Southern blot analysis of DNA from circulating mon onuclear cells gave a rearranged band for the immunoglobulin gene (JH) but not for TCR-beta. Cytogenetic analysis of marrow cells showed an abnormal karyotype involving numbers 1, 7, 10, 12, 14, 15 chromosomes.