Intereukin-8 Induces the Accumulation of B-Cell Chronic Lymphocytic Leukemia Cells by Prolonging Survival in an Autocrine Fashion

Several cytokines have been suggested to play a regulatory action on the neoplastic clone of patients with B-cell chronic lymphocytic leukemia (B-CLL) by interfering in the differentiation, proliferation, or death/survival pathways. Interleukin8 (IL-8) is a chemoattractant protein constitutively expressed at the mRNA level and released by B-CLL cells. In view of the presence of the IL-8 receptor mRNA and of specific IL-8 binding, confirmed also by Scatchard analysis using I-IL8, the study was extended to evaluate the possible regulatory role of this cytokine on B-CLL cells. 11-8 failed to show any in vitro proliferative effect on leukemic B-CLL cells. By contrast, the propidium iodide (PI) staining of the DNA content showed that IL-8 could prolong the survival of resting B-CLL cells in 11 of 16 cases studied. In the remaining 5 cases, 90.6% k 4.39% SD of the cells after culture remained viable and IL-8 could exert a significant death protection action after pretreatment with mol/L hydrocortisone, which reduced the percentage of viable B-CLL cells. The dose range of IL-8 capable of inducing the prolonging survival