Interleukin 1 (IL-1 alpha and IL-1 beta) induces differentiation/activation of B cell chronic lymphoid leukemia cells.

The effect of interleukin 1 (IL-1) was studied on leukemic cells from 12 patients with B cell chronic lymphoid leukemias including two cases of hairy cell leukemia (HCL), two cases of HCL-variant (HCL-V), one case of prolymphocytic leukemia (PLL), and seven cases of chronic lymphocytic leukemia (CLL). In most cases, IL-1 induced differentiation characterized by increments of sIg gamma+, sIg mu+ and PCA-1+ cells, and a decrement of CD5+ cells, and activation characterized by increments of CD23+ and HC2+ cells, but induced the proliferation of leukemic cells only in two HCL-V cases. Among these effects, increment of sIg+ cells was observed more frequently in non-CLL (4/5 cases) than in CLL (2/7 cases), and increments of sIg gamma+, CD23+ and PCA-1+ cells were induced more frequently by IL-1 beta than by IL-1 alpha. These results suggest that IL-1, especially IL-1 beta, plays a significant role in the differentiation and activation of leukemic cells, but has only a minor role as an extrinsic/leukemic cells in B cell chronic lymphoid leukemias, particularly those with more mature cells such as PLL and HCL.