FINE SPECIFICITY AND HEAVY CHAIN-V GENE USAGE OF ANTIBODIES TO THE PHOSPHORYLCHOLINE HAPTEN

In the course of the immune response to PC-KLH in mice, two major groups of anti-PC antibodies are expressed which differ in fine specificity, Id expression and isotype preference. Group I antibodies react predominantly with the PC moiety of the hapten and display mostly the T15 Id. On the other hand, Group II antibodies recognize the PC hapten including the azophenyl spacer to the carrier and are T15 Id-. In order to investigate the relationship between the two antibody populations, we analyzed the composition of 20 anti-PC hybridomas of all isotypes with respect to their fine specificity and VH gene segment utilization. Characterization of the antibodies by hapten inhibition analyses with PC and p-nitro-phenyl-PC indicated that eight hybridomas secreted Group I and 12 Group II antibodies. Southern blot analysis of total genomic DNA using a germ-line JH probe demonstrated that, with the exception of aPC-111-1, all Group II cells utilized gene segments distinct from those of Group I. In contrast to the restricted VH gene usage in Group I hybridomas, a more pronounced heterogeneity in H chain V gene rearrangements in Group II cells was observed. We found three groups of hybridomas with identical VH gene rearrangements. Two hybridomas used a VH gene segment of the 7183 VH gene family. Three λ I bearing Group II hybridomas shared a common hybridizing band. One of these, aPC-56-1, is known to utilize the same VH gene segment as MOPC 141. Finally, three cell lines, one of which (aPC-104-8) utilizes the VH1-DH-JH2 rearrangement, showed fragments of identical sizes. These results emphazise the independent origin of Group I and Group II anti-PC antibodies and demonstrate a larger germ-line repertoire of Group II antibodies as well as a less restricted use of particular VH genes relative to that of Group I. © 1990.