[Immunofluorescence study of reactions between the serum of patients with rheumatoid arthritis and components of connective tissue cellular elements].

By means of immunofluorescence using sera against three classes of human immunoglobulins (IgG, IgM, IgA), localization of the components (or one of the components) responsible for reaction of sera from patients with rheumatoid arthritis (RA) with connective tissue antigens was found to be in the cytoplasm of different kinds of cell elements of the connective tissue present in joints. Sera from RA patients collected at different stages of the disease reacted with connective tissue cell elements in titers of 1 : 64 to 1 : 1024, whereas sera from normal subjects (in 33% of specimens) reacted only to 1 : 8--1 : 16.