An observation on the humoral immunity in rheumatoid arthritis

The present paper dealt with the observation on 69 sera and 28 synovial fluids（SF）of patients With rheumatoid arthritis.Immune complexes（IC）and polyclonal antibodies were increased in both sera and SF.The increased circulating IC was not often accompanied by complement depletion.Sixty-six percent of IC fraction in sera consisted of aggregated IgG and the incidence of rheumatoid factor（RF）and C₃ in IC fraction was very low（28 and 17 percent respectively）.In contrast to sera,in synovial fluids,the negative relationship existed between IC and total complement activity,two and three immunoglobulins being found in 75 percent of IC fration.Most of those IC contained RF（96.4%）and C₃（89.9%）.The data illustrated that the IC in SF did differ from that in sera of RA patients.The molecular weight of IC in SF was larger and it had an ability to activated complement series resulting in tissue lesions.The fact that the levels of IC and RF titre in SF were higher than those in sera may illustrate that synovium might be responsible for the production of antibodies and auto-antibody,as well as the IC formation.It may also suggest that the abnormal immunity in the involved joints,perhaps,play an important role in the pathological process in rheumatoid arthritis.