[Changes in the synovial membrane in early diagnosed cases of rheumatoid arthritis. II. Immunohistochemical and serological studies].

To extend the histologic-histochemical examinations on so-called early cases of rheumatoid arthritis (RA, Geiler and Emmrich 1980) additional immuno-histochemical and serological tests were carried out on the same subjects. The purpose was to find out to what extent the well-known humoral immunological abnormalities of RA cases with fully developed disease (so-called late cases) occur in the early stage of RA. It was also aimed to determine their diagnostic and pathogenetic significance. The synovial membranes were tested immuno-histochemically for rheumatoid factor, immunoglobulins, and complement fixation for the complement factors C3, C4 and C9. In the serum the rheumatoid factor was assayed by the latex test and its immuno-globulin class specificity by means of an immunofluorescence test. In contrast to observations in the late cases, rheumatoid factors, immuno-globulins and complement deposits are found less often. In the class specificity test of rheumatoid factor in the serum there are considerably more positive cases than with the latex test. In the synovial membrane and in the serum there are positive cases also in juvenile RA-cases. For the diagnosis of early cases the immuno-histochemical demonstration of the rheumatoid factor in the synovial membrane is of great importance. The diagnosis RA may thereby the secured. --In the pathogenesis the accumulation of vasculitides with deposits of immune-complexes may be important. Possibly a vasculitis induced by immune-complexes represents the initial reaction of the rheumatoid synovitis. Since in the early cases little synthesis and deposits of immuno-globulins, rheumatoid factors and complements are found, it may be assumed that the more active humoral immunological activity of the synovial membrane of the late cases develops slowly during the course of the disease.