Abstract
High levels of immunoglobulins were produced in mice infected with larval A. suum, whereas antibody responses to an unrelated antigen administred 4 days before infection were suppressed. In the spleen, B cells remarkably increased, while T cells decreased during the first two weeks after the infection. The thymic atrophy and the elimination of immature thymocytes indicated the operation of systemic feedback-regulation. Lipopolysaccharide (LPS) carried over from the intestine was not concerned with the induction of the regulation. Activities of proinflammatory cytokines such as IL-6 and IFN were elevated in the infected mice, but the IL-1 alfa activity was rather diminished. The elevation of TNF-alfa activity was negligible, but it was enhanced by a challenge with a low dose of LPS. The IL-4 activity was undetectable either in sera or culture supernatants of splenocytes from infected mice. Results suggest that the perturbation of immune system may be caused in the process of a sequence of physiological reactions.
Key words: larval Ascaris suum infection; immunosuppression; immunoglobulin production; cellular inetics; thymic atrophy; cytokines.