Immunologic memory to phosphorylcholine (PC). VIII. Expression of the VH-12 gene product in the response to PC-keyhole limpet hemocyanin

Characterization of two monoclonal antibodies raised in Btk(xid) mice that recognize phosphorylcholine-bearing antigens from Trichinella and other helminths

This study investigated the binding properties of two monoclonal antibodies (mAbs US1 and US2) raised in (CBA/n x BALB/c)F1 (NBF1) Btk(xid) male mice. Both mAbs show unusual specificity for phosphorylcholine (PC)-containing TSL4 antigens of Trichinella. Specifically, and in contrast to mAbs raised in normal mice, US1 and US2 mAbs do not bind to artificial PC-protein conjugates and are not inhibited by either free PC or NPPC, although US2 was partially inhibited by NPPC at high concentration (10(-2) M). However, both mAbs completely abrogate the binding to Trichinella antigens of other anti-PC mAbs (e.g. BH8 and Mab-2). These results suggest that both US1 and US2 recognize complex PC-containing epitopes. The patterns of recognition of PC-bearing antigens from different helminths by US1, US2, Mab-2 and BH8 were broadly correlated with phylogenetic proximity. The closest similarities were observed between the members of the Trichinelloidea superfamily (Trichinella spiralis and Trichuris muris) and among the ascarids (Toxocara canis, Anisakis simplex, Hysterothylacium aduncum and Ascaris lumbricoides). However, US1 did not react with the filarial nematode Onchocerca volvulus and reacted only weakly with Onchocerca gibsoni, while US2 reacted only weakly with both species. Only BH8 recognized PC-bearing antigens from the trematode Fasciola hepatica and the cestode Bothriocephalus scorpii. These results suggest that PC is attached to identical or very similar structures on most different nematode species, although major differences exist with respect to helminth species from groups such as the trematodes and cestodes that are phylogenetically distant from the nematodes.

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 lambda 1 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 emphasize 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.

Antibody combining site heterogeneity within the response to phosphocholine-keyhole limpet hemocyanin

The memory response to PC-KLH is dominated by two antibody populations differing in fine specificity. Group I antibodies show affinity for both phosphocholine (PC) and p-nitrophenyl phosphocholine (NPPC). Group II antibodies exhibit significant affinity only for NPPC. Here, we describe the binding site characteristics of Group II antibodies and show that in recognizing NPPC these antibodies have a common requirement for the phenyl moiety, a negatively charged phosphate, and the trimethyl structure of the choline. However, Group II antibodies were found to differ in their requirement for the positively charged nitrogen of choline and thus could be divided into two subgroups. In contrast to Group II-A, Group II-B antibodies recognize not only NPPC but also its analog p-nitrophenyl-3,3-dimethyl butyl phosphate (NPDBP), which differs from NPPC by substituting a carbon for the positively charged nitrogen of the choline moiety. These results suggest that Group II-B antibodies do not require the positive charge in order to bind, although the binding constant, Ka, was increased when the nitrogen was present. Furthermore, heterogeneity within Group II antibodies was characterized by differences in binding to dinitrophenyl phosphocholine which has an additional phenyl ring and aminophenyl phosphocholine which has an amino group in place of the nitro group of NPPC. The results indicate that diversity in the memory response to PC-KLH is reflected in the Group II antigen-binding phenotype by antibodies which differ appreciably in their recognition of various structural aspects of the hapten.

A newly characterized group of anti-phosphocholine antibodies: group III antibodies

Four anti-phosphocholine (PC) monoclonal antibodies (MAbs) are described that can be clearly distinguished from group I and II anti-PC antibodies [Chang et al. (1982) J. Immun. 128, 702-706]. They bind optimally and suboptimally PC-histone coated ELISA plates equally well, in contrast to group I and II MAbs which bind much less well to suboptimally coated plates. On optimally coated plates their fine specificity for PC analogues is group II-like, whereas on suboptimally coated plates it is group I-like; group I and II MAbs each maintain their own characteristic fine specificity patterns on either type of plate. At the molecular level, all four MAbs utilize VK24 light chains and share a 5.2 kb rearranged band in Southern blot analysis (using a JH probe and EcoRI restricted DNA). The term "group III" is proposed to define and distinguish these anti-PC antibodies.