α-galactosylceramide may lead to an enhanced affinity immune response (IRC3P.459)

α-galactosylceramide (αGalCer) has been shown to stimulate B cell proliferation in mice, leading to enhanced antibody titers. We sought to discover whether, in addition to antibody titer, we could develop a higher affinity immune response in mice administered αGalCer in the context of our standard, adjuvant based immunization methodologies. Mice were immunized three times, every 4-6 weeks, with various antigens emulsified in Freund’s adjuvant. Test animals were administered αGalCer at the time of primary immunization, in addition to the antigen. Relative affinity was determined by testing serum antibody for reactivity to limiting concentrations of solution phase antigen. Results show that, for some antigen systems, administration of αGalCer does result in a trend toward a higher relative affinity vs. control animals. Pooled data from 3 antigen systems shows an average relative affinity of 2.105 nM for αGalCer mice vs. 3.134 nM for control mice. It was also observed, for one antigen system, that only those animals administered αGalCer developed a significant immune response. Our results indicate that administration of αGalCer at the time of primary immunization may lead to a slightly higher average affinity response in mice and can also be the difference between the development of a significant immune response vs. a very weak response.