Heterogeneity in terms of interleukin 4-dependent regulation of Fce receptor/CD23 expression on chronic B-lymphocytic leukemia cells

Abstract

To discriminate the stages of maturation arrest of leukemic B cells, we have investigated the cell surface expression of Fc epsilon RII (H107 antigen) on leukemic B cells from 6 patients with chronic type B-lymphocytic leukemia (B-CLL) by a double staining method combined with cytofluorometry, and their production of soluble Fc epsilon RII by an ELISA technique. Fc epsilon RII was expressed on mu+/delta- cells of case 5 as well as on mu+/delta+ cells of cases 1, 2 and 4, but not on mu+/delta+ cells in cases 3 and 6. The cultivation of leukemic cells with IL-4 not only increased the percentage of Fc epsilon RII+ cells but also enhanced the production of soluble Fc epsilon RII+ in most cases. However, IL-4 had no effects on mu+/delta-/Fc epsilon RII+ cells of case 5, which appeared to correspond to a rather late stage of normal B cell differentiation. Moreover, while leukemic B cells from case 1 spontaneously produced large amounts of soluble Fc epsilon R, the release seemed to be inhibited by an addition of IL-4. From our observations, it is speculated that IgM+/IgD+/Fc epsilon RII- leukemic B cells express surface membrane Fc epsilon RII and produce soluble Fc epsilon RII following stimulation with IL-4, and that IgM+/IgD-/Fc epsilon RII+ B-CLL cells may exist at some late stage of B cell differentiation.