Association of interleukin-6 and interleukin-8 with poor prognosis in elderly patients with chronic lymphocytic leukemia

In population studies, the relative survival in chronic lymphocytic leukemia (CLL) decreases with age. In this study, we demonstrated in a cohort of 189 patients from a CLL clinic that overall survival was lower in the sub-cohort of patients aged >= 70 years, but causes of death were similar for all age groups, being progressive CLL, secondary malignancies and infections. As normal individuals age, the plasma levels of inflammatory cytokines, such as interleukin-6 (IL-6) and IL-8, can increase. In our patients with CLL, IL-6, IL-8 and tumor necrosis factor-alpha (TNF-alpha) levels increased with age to a greater degree than in normal individuals, and the levels correlated closely with plasma beta(2)-microglobulin and with one another. In addition, in patients >= 70 years, IL-6 was found to be a better prognostic marker than immunoglobulin variable heavy chain gene (IgV(H)) status. In vitro studies demonstrated that IL-6 and IL-8 could enhance the binding of CLL cells to stromal cells, suggesting that their clinical activity may be mediated through their effects on the microenvironment. Thus, plasma IL-6 is an important prognostic marker for the elderly with CLL, and this study highlights that the utility of prognostic markers may depend on patient age.