Suppression of the Antibody Response to SRBC with F(ab′)2 and IgG in Vitro

Abstract

The role of the Fc portion of the IgG molecule in antibody-mediated regulation of the immune response is controversial (16, 17). If the Fc portion of the antibody molecule is removed by enzymatic digestion, the F(ab′)₂ portion is rapidly excreted by the kidneys and is lost from the circulation in intact animals (18). This rapid loss could possibly account for the reported difference in the efficiency of intact IgG and F(ab′)₂ in suppressing the immune response in vivo (7, 17). A tissue culture system avoids the problem of variable excretion. The experiments reported here demonstrate a significant difference in the efficiency of intact IgG and F(ab′)₂ (anti-SRBC) (a-SRBC) antibody in suppressing the immune response of cultured mouse spleen cells to SRBC in vitro, and suggest that the Fc portion plays an important role in antibody-mediated suppression of the immune response to SRBC.