Cytokine profile and immunomodulation in asymptomatic human T-lymphotropicvirus type 1-infected blood donors

The modulation of the immune response has been used as therapy for clinical disorders associated with human T-lymphotropic virus type 1 (HTLV-1) infec tion. In this study, the cytokine profile was evaluated in 26 asymptomatic HTLV-1 blood donors. Additionally, both the cell responsible for producing interferon-gamma (IFN-gamma) and the role of exogenous interleukin (IL)-10 in downregulating IFN-gamma production were studied. Cytokine levels were d etermined in supernatants of unstimulated lymphocyte cultures by enzyme-lin ked immunosorbent assay. The levels of IFN-gamma, tumor necrosis factor-alp ha, 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 aff ect IFN-gamma production, depletion of CD4(+) T cells significantly decreas ed IFN-gamma production. Furthermore, at a concentration of 2 ng/ml, IL-10 had only a minimum effect on IFN-gamma production, although at high concent rations (100 ng/ml), IL-10 decreased IFN-gamma 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 concen trations modulates IFN-gamma production in these patients.