Anti-phosphocholine hybridoma antibodies. I. Direct evidence for three distinct families of antibodies in the murine response.

Biochemical and serological studies were performed on more than 400 anti- phosphocholine (PC) hybridoma proteins (HP) derived from six strains of mice; 26 of these HP were examined in detail. All HP possessed specificity for PC, and all those tested contained an H-chain idiotypic determinant, V(H)-PC, which is shared by PC-binding myeloma proteins (BMP) and anti-PC antibodies. Among the HP, three well-defined and distinct families that correlated well with previous studies on serum anti-PC antibodies were identified. The largest group shared idotypic determinants, an L-chain isoelectric focusing (IEF) pattern, and a binding site specificity with the PC-BMP, T15. Using the same criteria, a second group was found to be strikingly similar to another PC-BMP, M603. The third group possessed an idiotypic determinant and an L-chain IEF profile similar to M511, but differences in binding site specificities were observed among the HP. The latter two groups contained members whose L-chain IEF profiles were not identical to other members of that group. Thus, among strains there is a remarkable degree of conservation among responding anti-PC antibodies, in both the kinds of anti-PC families that exist and the immunochemical and structural characteristics of various members within a family. Differences in at least one parameter were observed in each family, demonstrating that even a relatively restricted response is heterogeneous. However, this diversity seems to operate within certain constraints.