Production of intracellular IL-2, TNF-α, and IFN-γ by T cells in B-CLL

Background: Recent evidence indicates that the slowly expanding population of CD5(+) B cells that characterizes B-cell chronic lymphocytic leukemia (B-CLL) could be related to defects in the response to cytokine produced by T cells that regulate apoptosis. We studied the intracellular expressions of interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) in T-helper 1 cells (Th1 response) of B-CLL. Methods: Peripheral blood mononuclear cells from 21 healthy individuals and purified T cells from 21 early-stage and 15 late-stage B-CLL patients were activated with phorbol myristate acetate and ionomycin. The Th1 cytoplasmic cytokines were evaluated in CD4(+) and CD8(+) T cells by flow cytometry. Results: The percentages of CD4(+) and CD8(+) T cells positive for IL-2 were significantly lower in B-CLL patients than in healthy individuals (P = 0.030 and 0.049, respectively). No significant differences in TNF-alpha or IFN-gamma intracellular expressions were found between patients and healthy individuals. TNF-alpha- and IFN-gamma- expressing COB T cells were disease stage dependent, being significantly higher in late-stage patients (P < 0.001 for both cytokines). Conclusions: Our present observations suggested that Th1 cytokines may be of major importance in the pathogenesis of B-CLL. Cytometry Part B (Clin. Cytometry) 56B:23-29, 2003. (C) 2003 Wiley-Liss, Inc.