Immune response in the hamster. VIII. Ig class differences in susceptibility to tolerance induction

A hemolytic plaque assay was used to quantitate the antibody response of the Syrian hamster after immunization with hen egg albumin (HEA). Whereas HEA in complete Freund's adjuvant (HEA-CF) induced a prolonged heterogeneous (IgM, IgG1 and IgG2) antibody response, the response to soluble HEA in saline (HEA-S) differed in that: 1)both the primary and secondary responses were restricted to the IgG1 class; 2)the IgG1 primary response was cyclical with PFC peaks on days 9 and 16; 3)although an anamnestic secondary response was demonstrated, no further augmentation was noted after tertiary and quaternary boosters; 4)the booster response was transient reaching a peak after 48 hr and declining to low levels within 7 days. Adoptive transfer of lymph node cells to irradiated recipients followed by challenge with HEA-CF revealed: 1)that HEA-S-treated donor cells were primed for an IgG1 response because anamnesis was seen 7 days after challenge, yet on day 21, IgG1 PFC were 20-fold less than that of controls; 2)recipients of HEA-S treated cells showed profound suppression of both IgM and IgG2 PFC on days 14 and 21. These studies indicate that soluble antigen induced in hamsters a state of complete tolerance of IgM and IgG2 classes whereas the anamnestic response of the IgG1 class remained intact.