Expression of Myelomonocytic Antigens on Chronic Lymphocytic Leukemia B Cells Correlates With Their Ability to Produce Interleukin 1

We analyzed the expression of myelomonocytic-associated antigens on lymphocytes from B cell chronic lymphocytic leukemia (B-CLL) patients. Blood mononuclear cells were depleted of monocytes by one-step Percoli density gradient centrifugation and tested for antigen expression by fluorescent microscopy and flow cytometry. The reactivity of patient lymphocytes was as follows: 26 of 31 were positive for CD14 (Myr), 22 of 31 for a monocyte Fc receptor (MFC-1), 22 of 31 for CD11b (C3bi receptor), eight of 31 for CD15 (Leu-MD, five of 18 for CD13 (My 7), seven of 18 for My 9, and five of 30 for Mo 2. The B lymphocytes of B-CLL patients were also tested for the ability to produce interleukin 1 (IL-1) after depletion of monocytes and T lymphocytes. In 13 of 17 cases, B lymphocytes of patients produced IL-1 as detected in a mouse thymocyte proliferation assay and, in selected cases, a radioimmunoassay specific for IL-1β. The 13 cases that produced IL-1 were also positive for the expression of one or more myelomonocytic-associated antigens, whereas the four cases that did not produce IL-1 lacked expression of these antigens. In conclusion, the malignant B cells of B-CLL patients frequently express a variety of antigens generally considered specific for myelomonocytic cells, and expression of these antigens is associated with the ability to produce IL-1.