Antilymphocyte antibodies in rheumatoid arthritis.

The presence of cold and non-cold reacting antilymphocyte antibodies of IgG class, active against allogeneic T lymphocytes deprived of Fcgamma receptor bearing cells, was investigated by indirect immunofluorescence (IF) and by microlymphocytotoxicity in 50 patients with Rheumatoid Arthritis (RA). 6/50 rheumatoid sera have shown the presence of anti-T-lymphocyte antibodies against 8/50 positivities found when the whole lymphocyte population was employed as the target in IF test. The positive sera were also examined by microlymphocytotoxicity test and the correlation with the number of lymphoid cells in peripheral blood was studied. In only one case (RA + Sjogren's syndrome) a positive IF test, in vitro cytotoxicity and in vivo lymphopenia were observed. In the other IF positive cases neither lymphopenia in vivo nor lymphocytotoxicity of the sera were observed; these results can be due to either the presence of cold or not complement fixing antilymphocyte antibodies.