Cytokine Profile and Immunomodulation in Asymptomatic Human T‐Lymphotropic Virus Type 1‐Infected Blood Donors

Summary: The modulation of the immune response has been used as therapy for clinical disorders associated with human T‐lymphotropic virus type 1 (HTLV‐1) infection. In this study, the cytokine profile was evaluated in 26 asymptomatic HTLV‐1 blood donors. Additionally, both the cell responsible for producing interferon‐&ggr; (IFN‐&ggr;) and the role of exogenous interleukin (IL)‐10 in downregulating IFN‐&ggr; production were studied. Cytokine levels were determined in supernatants of unstimulated lymphocyte cultures by enzyme‐linked immunosorbent assay. The levels of IFN‐&ggr;, tumor necrosis factor‐&agr;, IL‐5, and IL‐10 were higher in supernatants of the lymphocyte cultures taken from HTLV‐1‐infected donors than in those taken from healthy subjects. Although depletion of CD8+ T cells and natural killer cells did not affect IFN‐&ggr; production, depletion of CD4+ T cells significantly decreased IFN‐&ggr; production. Furthermore, at a concentration of 2 ng/ml, IL‐10 had only a minimum effect on IFN‐&ggr; production, although at high concentrations (100 ng/ml), IL‐10 decreased IFN‐&ggr; production by 50% in HTLV‐1‐infected individuals. These data indicate that both T helper 1 and T helper 2 cytokines are elevated in HTLV‐1 infection and that IL‐10 in high concentrations modulates IFN‐&ggr; production in these patients.