TNF and infection: Vernon Pauillac and Merian [20] have shown that mononuclear macrophages of peripheral blood of hamster infected with a virulent variant of Leptospira interrogans secrete proinflammatory cytokines (TNF-α) with a Th1 (IL-12) profile in the first hour, predominating until the fourth day after infection, whereas a Th2 profile appears after 24 hours of infection.