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Generation of antibody diversity. IV. Variation within single clones of antibody-forming cells developing in vivo
Previous experimental work demonstrated that clonal variation occurs in vitro. The present experiments were designed to test for clonal variation in vivo. B cells were transferred at limiting dilution, with antigen, into irradiated recipients. Seven days later spleens were assayed for plaque-forming cell (PFC) colonies. Control experiments showed that these PFC colonies were clones, that is, they were derived from a single B cell precursor. When the clones were analyzed for heterogeneity of the PFC population, using cross-reactivity on various mixtures of red blood cells as a method of detecting differences in antibody specificity, from 23-83% of the clones contained variants. By adjusting the amounts of helper activity and antigen available to a developing clone, we have been able to influence this variation; high levels of help and/or antigen favor pure clones, while low levels of either produce mainly mixed clones.
Previous experimental work demonstrated that clonal variation occurs in vitro. The present experiments were designed to test for clonal variation in vivo. B cells were transferred at limiting dilution, with antigen, into irradiated recipients. Seven days later spleens were assayed for plaque-forming cell (PFC) colonies. Control experiments showed that these PFC colonies were clones, that is, they were derived from a single B cell precursor. When the clones were analyzed for heterogeneity of the PFC population, using cross-reactivity on various mixtures of red blood cells as a method of detecting differences in antibody specificity, from 23-83% of the clones contained variants. By adjusting the amounts of helper activity and antigen available to a developing clone, we have been able to influence this variation; high levels of help and/or antigen favor pure clones, while low levels of either produce mainly mixed clones.