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

Abstract

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‐α (TNF‐α), and interferon‐γ (IFN‐γ) 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‐α or IFN‐γ intracellular expressions were found between patients and healthy individuals. TNF‐α‐ and IFN‐γ–expressing CD8 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.