GENERATION AND MOLECULAR CHARACTERIZATION OF MONOCLONAL IGG4 RHEUMATOID-FACTOR FROM A PATIENT WITH RHEUMATOID-ARTHRITIS

Objective-To characterise IgG4 rheumatoid factor (RF) at the molecular level from a patient with rheumatoid arthritis. Methods-B tells were cloned from the peripheral blood of a patient with arthritis, using EB virus transformation. The supernatants of the clones were screened fo r IgG RF activity by ELISA. Nucleotide sequences of the expressed immu noglobulin heavy and light chain genes of one IgG RF producing clone w ere determined by direct sequencing of the products of a polymerase ch ain reaction. Results-One clone producing monospecific IgG4 RF was obt ained. Sequence analysis of the heavy and Light chain genes suggested the accumulation of somatic mutations resulting in amino acid replacem ent in complementarity determining regions. Conclusions-The results ma y suggest an antigen driven response in the generation of IgG4 RF in r heumatoid arthritis disease processes.