Antigen induced rheumatoid factors: characteristics of monoclonal rheumatoid factors produced after protein and carbohydrate immunization.

Abstract We generated a panel of monoclonal rheumatoid factors (MRF) from BALB/c mice immunized with ovalbumin, dextran or group-A-carbohydrate. Individual MRF were analyzed in terms of their binding to the four isotypes of murine IgG, isotypes of human IgG, and rabbit IgG, the idiotypes they express, and the V H gene families they employ. We found that antigen induced rheumatoid factors could be divided into three different families based on their isotypic specificity for murine IgG: an IgG1 binding family, and IgG3 binding family, and a family of MRF that bound all four murine isotypes. Rheumatoid factors belonging to all three families were isolated from mice immunized with carbohydrate antigens. The rheumatoid factors isolated from protein immunized mice all belonged to the IgG1 binding family. We were able to define two cross-reactive idiotypes among MRF, one expressed by a subgroup of the IgG1 binding family, and a second cross-reactive idiotype expressed by some members of the pan-binding family. We determined V H gene use in five of six MRF belonging to the IgGI binding family and four of four members of the pan-binding family. Four of the IgG1 binding rheumatoid factors and three of the pan-binding rheumatoid factors utilize the J558 V H gene family. Rheumatoid factors produced after carbohydrate antigen immunization, as compared with those generated by protein immunization, are diverse in their isotypic specificity, and show a greater ability to bind heterologous IgG.