Clonal Nature of the Immune Response to Phosphorylcholine

Abstract The fine specificity of anti-phosphorylcholine antibodies was studied in different rodent species and 17 different inbred mouse strains. Measurements of the relative affinity and specificity of the antibodies were derived from a hemolytic plaque-inhibition assay with phosphorylcholine and two of its analogues, glycerophosphorylcholine and choline, as inhibitors. Within a given species, inhibition of plaque-forming cells was accomplished within a narrow range of ligand concentration and little individual variation was seen. Moreover, no changes in either the slopes or relative position of the inhibition curves occurred at different times after immunization. These findings suggest that a restriction in heterogeneity of the anti-phosphorylcholine antibodies exists in each of the rodent species. However, striking species-specific differences were observed in the binding characteristics of antibodies from different species of rodents.