Effects of recombinant IFN-α on the production of IL-10 and IFN-γ by CD4⁺ T cells. Graded doses of recombinant IFN-α (Schering-Plough, Innishannon, Ireland) were added to CD4⁺ T cells purified from peripheral blood of five healthy volunteers and stimulated with either PMA (1 ng/mL) and anti-CD28 MoAb (1 μg/mL) (•), or the CLB-T3/4.1 anti-CD3 MoAb (100 ng/mL) cross-linked on fibroblasts transfected with the B7-1 gene (▪), as previously described.2 After 48 hours, culture supernatants were harvested for determination of immunoreactive IL-10 and IFN-γ by ELISA, as previously described.2 Data are shown as mean ± SEM.