Modulation of the Immune Response by Pretreatment of Antigen with Complement

Abstract

Abstract It is known that inactivation of C3 leads to a decreased immune response both in vivo and in vitro, and it has been concluded that C3b is involved in the generation of an immune response to T-dependent antigens (reviewed by Pepys, Transplant. Rev. 32, 93 (1976)). Thus it appeared of interest to investigate whether complement components other than C3 influence the magnitude of an immune response. Sheep erythrocytes were pretreated with IgM anti-Forssman antibody and subsequently reacted with either purified complement components or whole guinea pig serum. 2 × 108 SRBC (or ghosts, respectively, in the case of lysed SRBC) were injected, either i.v. or i.p. into naive NMRI or (B6D2)F1 mice. The immune response was assayed by either titrating antibody concentrations in serum or by the Jerne Plaque technique. Injection of E, EA(IgM), EAC1-7 caused similar immune responses. On the other hand, injection of EA(IgM) lysed by complement (E*) led to a 10-fold decrease of the immune response.