TNF and infection: But the possibility of an early increase in IFN-α sensitizing CD8+ T cells to produce IFN-γ during later stages of infection cannot be ruled out [32, 37, 38].TNF-α is known to be secreted by macrophages, Thl cells, mast cells and antigen-specific CTLs when encountering viral antigens which help in proliferation and differentiation of T cells, B cells, macrophages, NK cells and fibroblasts [32].