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-γ (IFN-γ) and the role of exogenous interleukin (IL)-10 in downregulating IFN-γ production were studied. Cytokine levels were determined in supernatants of unstimulated lymphocyte cultures by enzyme-linked immunosorbent assay. The levels of IFN-γ, tumor necrosis factor-α, 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-γ production, depletion of CD4+ T cells significantly decreased IFN-γ production. Furthermore, at a concentration of 2 ng/ml, IL-10 had only a minimum effect on IFN-γ production, although at high concentrations (100 ng/ml), IL-10 decreased IFN-γ 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-γ production in these patients.