Modulation of Hapten-Specific Antibody Responses with Anticarrier Antibody: I. Differential Effects of IgM and IgG Anticarrier on Primary Direct and Indirect Hapten-Specific Plaque-Forming Cells 1

Summary

Immunization of mice with TNP coupled to ORBC resulted in a TNP-specific antibody response. TNP-specific direct and indirect PFC in the spleens reached a maximum level 5 days after injection. Passively administered anticarrier antibodies injected with the hapten-carrier conjugates were found to modulate the primary PFC response to hapten. Three days after injection, both classes of carrier-specific antibody induced potentiation of hapten-specific direct and indirect PFC. On Day 5, however, IgM and IgG had opposite effects on the TNP-specific response. Carrier-specific IgM produced a three- to fourfold increase in both direct and indirect hapten-specific PFC over animals injected with the hapten-carrier conjugates alone. In contrast, carrier-specific IgG, at relatively high concentrations, suppressed the hapten-specific indirect PFC but had little effect on direct hapten-specific PFC.