Abstract
The effect of a monoclonal antibody against IL-4 (11B11) on oral tolerance was investigated. Oral tolerance was induced by feeding mice with hen egg lysozyme (HEL) before immunization with HEL. 11B11 was ip injected 30 min before oral administration of HEL. The results showed that the oral administration of HEL suppressed immune responses to the antigen including DTH responses, production of both isotypes of IgG 1 and IgG2a antibodies, and proliferation of lymph node cells in a dose-dependent manner. These suppression were associated with a marked reduction of IFN-γ secretion and a partial decrease in IL-4 production by lymphoid cells. The treatment of the tolerant animals with 11B11 significantly blocked the suppression of DTH responses, IgG2a antibody production, and proliferative responses as well as IFN-γ secretion. In contrast, the monoclonal antibody facilitated the suppression of anti-HEL IgG1 antibody production and IL-4 secretion. Thus, oral antigens appear to induce not only Th1 but also Th2 cell tolerance and the neutralizing IL-4 with anti-IL-4 antibodies seems to reverse the suppression of Th1 cell responses, while the antibodies further reduce Th2 cell responses in oral tolerance, indicating the implication of IL-4 in the oral tolerization of Th1 cells.
