MOLECULAR ANALYSIS OF CARBOHYDRATE ANTIGEN-INDUCED MONOCLONAL IGM ANTI-IGG ANTIBODIES (RHEUMATOID FACTORS)

Light and heavy chain variable regions of 11 monoclonal rheumatoid factors (MRF) produced after carbohydrate antigen immunization, and one MRF produced after protein immunization have been sequenced. Most carbohydrate antigen induced MRF utilized light chains that were homologous to light chains of MRF obtained from protein immune or LPS stimulated mice, and MRF derived from the autoimmune MRL/lpr mouse strain. V(H) gene usage was diverse for carbohydrate antigen induced MRF that bound all four isotypes of IgG, or that bound only the IgG3 isotype. In contrast V(H) gene use among our panel of MRF that bound the IgG1 isotype appeared restricted. Four of the five IgG1 binders used V(H) genes that were highly homologous to the V(H) nucleotide seqeunce of a gene encoding an NP binding monoclonal antibody. Our study confirms. the use of a particular group of light chain genes among murine MRF, confirms that there is diversity in the heavy chain genes utilized among MRF, and suggests that a gene(s) homologous to the V(H) NP 23 J558 gene may be preferentially associated with murine MRF specificity for the IgG1 isotype.