Effect on tolerance induction of the mode of attachment of the hapten the carrier.
In this study we have investigated the role played by the mode of attachment of the hapten on autologous IgG in the induction of carrier-determined tolerance. Three conjugates of the dinitrophenyl hapten and mouse gamma-globulin were prepared: 1) DNP-epsilon-lysine-MGG, 2) DNP-azo-MGG (which binds to histidine and tyrosine), 3) DNP-must-MGG (which binds to the carboxyl groups of glutamic or aspartic acid). DNP was also bound to the immunogenic carrier keyhole limpet hemocyanin (KLH) by the three different linkages. The three DNP mouse-gamma-globulin conjugates were used to induce tolerance and immediately thereafter the animals were immunized with various DNP-KLH conjugates. Antibody response was tested by a modiciation of the Jerne plaque assay. It was found that DNP-epsilon-lysine-MGG induced tolerance to both DNP-epsilon-lysine-KLH and to DNP-azo-KLH. In contrast, neither DNP-azo-MGG nor DNP-must-MGG induced tolerance to DNP-epsilon-lysine-KLH or to DNP-azo-KLH and DNP-must-KLH, respectively. Clearance studies showed no differences in the catabolic rate of the various hapten mouse gamma-globulin conjugates as compared to unconjugated MGG. However, although DNP-must-MGG and DNP-azo-MGG were not tolerogenic, they were immunogenic. In conclusion, this study demonstrated that not only the nature of the carrier but the mode of hapten binding to his carrier are critical for the induction of hapten specific tolerance.