Observations on the eosinophilia of certain patients with rheumatoid arthritis

Abstract

Abstract In a retrospective study of 45 cases of rheumatoid arthritis selected for their severity or for elevated titers of rheumatoid factor, unexplained eosinophile counts of 5% or greater were encountered in 40%. Certain extra‐articular manifestations of rheumatoid arthritis were found in higher incidence in the group of patients with eosinophilia. The most notable of these were vasculitis, pleuropericarditis, pulmonary fibrosis and subcutaneous nodules. The eosinophilia was present for variable periods of time, sometimes persisting at elevated levels for several years or alternatively appearing in brief episodes. In a number of patients, the appearance in time of some extra‐articular manifestations was coincident with eosinophilia. Two patients had extreme elevations in the number of eosinophiles. The eosinophiles of one patient, studied in detail, showed inclusions, which by immunofluorescent microscopy, contained γG‐globulin, γM‐globulin and rheumatoid factor. The serum of this patient when incubated with another eosinophile preparation induced the formation of inclusions. Various mechanisms were discussed in which the eosinophilia is related to possible immune events occurring in the course of rheumatoid arthritis.