Abstract
A reaction has been demonstrated between extracts of synovial cells removed from intact rheumatoid knee joints and autologous leucocytes. The cell mediated immunity test system used was leucocyte migration inhibition. Variable reactions were found with a spectrum of allogeneic extracts when donor leucocytes came from married or transfused females or transfused males. Leucocytes from healthy (nontransfused) males showed no reaction with any of the extracts. As a period of cell culture was used prior to preparation of this extract to remove nonspecific inhibitory substances, native immunoglobulins, and complexes, the data are best explained by the presence of a foreign pathogen or altered cell component in the synovial cells of these rheumatoid patients.