Fine specificity and idiotype expression of antiphosphorylcholine IgE and IgG antibodies

Abstract

The immune response to the phosphorylcholine (PC) hapten elicited in BALB/c mice by PC‐keyhole limpet hemocyanin (KLH) is composed of 2 groups of antibodies with specificity to PC and phenyl‐PC, respectively. They were designated as group I and group II anti‐PC antibodies. In this report we demonstrate that anti‐PC IgE antibodies elicited by PC‐KLH or PC‐ovalbumin belong to the group II and do not express the T15 idiotype. Anti‐PC IgG₁, IgG_2a, and IgG_2b antibodies express group I characteristics in the primary response and bear the T15 idiotype. Later, after 5 weeks and 3 injections of PC‐KLH or PC‐ovalbumin, a change in these isotypes to group II antibodies is observed. In contrast, anti‐PC IgE is a group II antibody throughout progression of the immune response. The regulation of group I and group II antibody expression in serum is independent of the genetic background of the animals.