Participation of Granulocyte‐specific Antinuclear Factors in Rheumatoid Joint Fluid Cryoprecipitates

Abstract

Participation of granulocyte-specific antinuclear factors in rheumatoid joint fluid .cryoprecipitates. Acta path. microbiol. scand. Sect. c, 83: 265-272, 1975. Cryoglobulins, isolated from synovial fluids of 42 rheumatoid arthritis patients and 18 osteoarthrosis patients were studied immunochemically and serologically. T h e concentrations of total protein, IgG and IgA were significantly higher in the rheumatoid cryoglobulins, while complement components were rare in both types of cryoglobulins. Fibrinogen antigens were commonly demonstrated in both rheumatoid and osteo-arthrosis cryoglobulins. Granulocytespecific antinuclear factors belonging to the IgG and/or IgM classes were found in 62 per cent of the rheumatoid but none of the osteo-arthrosis cryoglobulins. Organ-nonspecific antinuclear factors were detected in 30 per cent and antiglobulins in 24 per cent of the rheumatoid cryoglobulins, while osteo-arthrosis cryoglobulins were devoid of such activity. I n a few cases antinuclear factors and antiglobulins were solely detected in the cryoglobulin and not in the corresponding joint fluid. A comparison between cryoglobulin and joint fluid IgG as to the relative content of IgG antinuclea? factors in paired positive specimens may indicate enrichment of the cryoglobulins with granulocyte-specific and organ-nonspecific antinuclear factors. O u r data are compatible with the notion that rheumatoid joint fluid cryoglobulins, at least in part, represent cold-insoluble immune complexes composed of antinuclear factors and antiglobulins as well as nuclear antigens as shown by others.Rheumatoid synovitis may be regarded as an extravascular immune complex disease (38) featuring immunoglobulin (Ig) and complement deposition in the synovial membrane as shown by direct immunofluorescence (4, 22, 25) and elution studies (6, 23), presence of inclusions containing similar proteins 17 Acta path. microbiol. scand. Sect. C, 83, 4