The immunological role of antigen-binding cells

A well characterized antigen-binding cell population can yield important insights into antigen-induced activation events. But data interpretation must take into account the heterogeneity of these populations. The maturity of ABC and the proportion belonging to the various T and B-cell subsets depends on the source and on the conditions of the antigen-binding cell assay. There are a variety of useful methods for isolating highly purified populations of B-ABC, but the highest purity is achieved only by sacrificing yield and skewing the composition of the population. The direct demonstration that virtually every LPS-stimulatable precursor of IgM or IgG secreting cells in the SRC-ABC population is a precursor for specific antibody producing cells establishes the commitment of SRC-ABC to the SRC response. Although the majority of spleen B-ABC respond to immunization in vivo by switching surface isotypes and accelerating receptor turnover, the more stringent requirements for further differentiation to antibody production are still under active investigation(27). By investigating the biochemical events that take place in ABC during immune responses in vivo and in vitro, and pursuing parallel studies of cloned functional cell lines responding to antigen through surface receptors, wer may eventually understand the classical interactions of cellular immunology in terms of physiological changes in the antigen-reactive cells.