The role of B-cell memory in secondary IgG and IgM responses.

Mice were primed with the hapten 3-nitro-4-hydroxy-5 iodophenacetic acid (NIP) conjugated to chicken globulin (cg) and were boosted 2, 6, or 12 months later with CG conjugates of the related haptens 3,5-diiodo-4-hydroxyphenacetic acid (DIP) or 3-nitro-4-hydroxphenacetic acid (NP). Accelerated secondary responses were demonstrated both in the 7S and 19S class. Fine-specificities of secondary-response antibodies were studied by the hapten inhibition method of haptenated bacteriophage inactivation. 7S antibodies were found to have the fine-specificity of anti-NIP antibodies regardless of whether DIP or NP was the booster hapten ('original antigenic sin'). 19S antibodies had the fine-specificity of anti-DIP when DIP was the booster hapten. NP as the booster hapten resulted in 19S antibodies whose fine-specificity was intermediate between anti-NIP and anti-NP. A strong B-cell memory could thus be demonstrated in the 7S antibody response and a weak B-cell memory in the 19S antibody response.