CD4 and autoimmune disease: Because increases in the frequencies of IFN-γ+IL-17+ have been positively correlated with disease severity in several models of inflammatory and autoimmune diseases, we hypothesized that the decreased total numbers of IFN-γ+ and IL-17+ CD90+CD4+ T cells in HKTC-immunized mice, relative to T. cruzi-infected mice, might be partially attributable to a decrease in this IFN-γ+IL-17+ population.