Synovial Cell Antigens – Production of Heterologous Anti-Human Synovial Cell Sera and General Reactivities of the Antisera

Antisera to cultured human synovial cells were produced in several rabbits by a variety of immunization procedures. The antisera were assayed by a number of immunologic techniques for specificities against live synovial and other fibroblastic cell lines and against additional antigen sources including human serum and synovial fluid, and fetal calf serum. While the antisera reacted well and with the same titers to all synovial cell lines, reactivities varied with several nonsynovial cell lines showing that synovial tissue-derived cells are antigenically different from other tissue fibroblastic cell strains. Also, the major antigens cross-reactive between synovial and certain other fibroblastic cell lines were partially defined as those in or cross-reactive with fetal calf serum and human serum or plasma components. The differential reactivities of the antisera demonstrated that the antibody specificity populations were markedly affected by the immunization manipulations. Methods for analyzing those differences are presented by defining specificity and reactivity indices. The antisera to the synovial cells distinguished 7 electrophoretically distinct reactivities in human serum or plasma, synovial fluid, and in fetal calf serum. 1 antigen was identified as fibronectin, 3 as components of fetal calf serum and 3 additional unidentified human serum cross-reactive antigens.