Suppression of macrophage interleukin-12 and tumour necrosis factor-alpha production in mice infected with Toxocara canis

Toxocara canis induces a predominantly Th2 type response with enhanced amou nts of interleukin (IL)-4 and reduced amounts of interferon (IFN)-gamma in infected mice. In this study, we investigated the macrophage function of T, canis-infected mice from the standpoint of cytokine production. C3H/Hen mi ce were infected with T. canis by oral administration of embryonated eggs. Ten days after infection, macrophages were obtained from spleen and periton eal cavity, were cultured with lipopolysaccharide, and cytokines in the cul ture supernatant were evaluated with enzyme-linked immunosorbent assay. Mac rophages from T. canis-infected mice produced IL-1 and IL-6 equvalent to ma crophages from normal mice. The production of IL-10 and tumour growth facto r (TGF)-beta was enhanced, but IL-12 and tumour necrosis factor (TNF)-alpha production was diminished. The addition of IFN-gamma, anti-IL-10 antibody, anti-TGF-beta antibody or indomethacin did not restore the production of I L-12 and TNF-alpha by macrophages from T. canis-infected mice. Furthermore, the stimulation of normal macrophages with T. canis antigen in vitro induc ed IL-1 alpha, IL-6, IL-10 and TGF-beta, but not IL-12 and TNF-alpha. These results indicate that cytokine producing pattern of macrophages is altered by T. canis-infection, and this altered macrophage function may play an im portant role in the modification of the immune response to T. canis.