THE ROLE OF INTERLEUKIN-10 (IL-10) IN CHRONIC B-LYMPHOCYTIC LEUKEMIA - IL-10 PREVENTS LEUKEMIC-CELLS FROM APOPTOTIC CELL-DEATH

We examined the possible role of interleukin 10 (IL-10) in the pathoge nesis of human chronic B-lymphocytic leukemias (B-CLL). With the use o f an in vitro culture technique, we found that IL-10 enhanced the surv ival of B-CLL cells in a dose-dependent fashion by inhibiting the proc ess of apoptotic cell death. This was demonstrated by transmission ele ctron microscopy and DNA gel electrophoresis. Flow cytometric and immu noblot analyses showed that IL-10 did not significantly upregulate bcl -2 expression as compared with control cultures. B-CLL cells were also found to spontaneously release IL-10 in cultures, and serum IL-10 lev els were elevated in five of the eleven B-CLL patients. These findings suggest that IL-10 acts as an autocrine growth factor for B-CLL cells and cytokine-based therapy might be a new approach for the treatment of B-CLL.