The Effects of carrier-specific helper T-cell tolerance on antibody avidity in the anti-hapten response

Rats rendered tolerant to ultracentrifuged sheep γ-globulin (SGG) have been shown to make a poor anti-trinitrophenyl (TNP)-specific antibody response upon challenge with TNP-SGG in complete Freund's adjuvant (CFA). We have been able to use this carrier-tolerance system in studying specific helper T-cell unresponsiveness to IgG and IgM antibody responses. By using the plaque inhibition technique to measure antibody avidity, we found that there appears to be no difference in the avidity of antibody responses to TNP between the SGG-tolerant and control groups when both are challenged with TNP-SGG in CFA. This was found to be true in both the 19 and 7S antibody responses in vivo as well as in an adoptive transfer model. In addition, studies on the maturation of 19 and 7S antibody responses showed no differences in antibody avidity between carrier-tolerant and control groups. These findings imply that carrier-specific helper T cells do not play a controlling role in determining whether high- or low-avidity hapten-specific B-cell precursors will proliferate in response to challenge with a hapten-carrier conjugate.