STUDY OF COMPLEMENT-FIXATION BY RHEUMATOID-FACTOR USING A HEMOLYTIC ASSAY SYSTEM

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 28  (2) , 204-211
Abstract
Complement fixation by rheumatoid factor (RF) in sera from rheumatoid arthritis patients was investigated by means of a hemolytic assay system employing sheep erythrocytes (SRBC) coated with reduced and alkylated rabbit Ig[immunoglobulin]G anti-SRBC antibody. Hemolysis was almost invariably detected with RF-positive sera, whereas hemolysis was not observed with RF-negative sera. It was evident from a marked increase in hemolysis, obtained following isolation of IgM-RF of high purity from several RF-positive sera, that the full in vitro complement-fixing ability and hence lytic potential of RF in serum is masked. Parallel observations were also made with synovial fuids. The inhibition of hemolysis by RF in sera and synovial fluids commonly involved a reduction in degree of lysis at high concentration of test material as well as a more generalized inhibition in overall percentage lysis. Complete replication of typical RF-positive serum and synovial fluid patterns of lysis on dilution was achieved by addition of heat-aggregated human IgG to isolated IgM-RF preparations and demonstated that the 2 inhibitory effects are separable in terms of complement depletion and reduction of free rheumatoid factor antibody activity, respectively.