Fine specificity and idiotype expression of antiphosphorylcholine IgE and IgG antibodies

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, IgG2a and IgG2b 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.