Resting B cells are not antigen-presenting cells in the induction of oral tolerance of specific Th2 immune responses in mice

Background: It has been shown that antigen presentation by resting B cells can induce tolerance to intravenously administered protein antigens, but th e role of resting B cells in the induction of oral tolerance is unclear. Me thods: Mice continuously treated since birth with rabbit anti-mouse IgM ser um for 5 weeks were depleted of B cells, When 4 weeks old, B cell-depleted mice drank 10% chicken egg white (EW) for 5 days. Ten weeks later, they wer e immunized with 10 mu g of ovalbumin in alum and their T helper 2 (Th2) im mune responses were tested. Results: Th2 cell-mediated IgE and IgG1 antibod y responses and spleen cell production of IL-4 and IL-5 were suppressed by prior EW feeding during anti-Igm treatment. When anti-IgM-treated spleen ce lls collected 1 week after EW ingestion were transferred to naive recipient s, active suppression of Th2 immune responses was also demonstrated. Conclu sions: Although resting small B cells aggregate in the mantle zone of folli cles of intestinal Peyer's patches, the present data suggest that they are not antigen-presenting cells in the induction of oral tolerance of Th2 immu ne responses to oral antigens. Copyright (C) 2000 S. Karger AG, Basel.