Some Leishmania molecules, such as lipophosphoglycan (LPG), seem to repress IL1-α (Frankenburg et al., 1990), IL-1-β (Hatzigeorgiou et al., 1996) and IL-12 (Carrera et al., 1996; Belkaid et al., 1998; Weinheber et al., 1998) production during infection via TLR2. This evidence concerns the gene IL1A and infection.