The Felty syndrome: a case-matched study of clinical manifestations and outcome, serologic features, and immunogenetic associations.

Thirty-two patients with the Felty syndrome, defined by the presence of rheumatoid arthritis, splenomegaly, and neutropenia, have been studied in comparison with 32 patients with rheumatoid arthritis matched for age, sex, and disease duration, and 9 patients with rheumatoid arthritis and idiopathic neutropenia. Patients with the Felty syndrome had severe destructive arthritis, which progressed during follow-up despite little evidence of objective synovitis, and a higher frequency of extra-articular manifestations, including vasculitis. Bacterial infection tended to occur in patients with the lowest neutrophil count but continued to occur in some despite normalization of the WBC. Prognosis was poor and 8 deaths occurred, predominantly from sepsis. Serologic features were prominent. High titers of IgG rheumatoid factor and circulating immune complexes characterized patients with persistent neutropenia. A family history of rheumatoid arthritis was more common in patients with the Felty syndrome. The association with HLA DR4 was very strong; in addition there was an increased frequency of the DQw3 variant, 3b, suggesting that HLA Class II genes in linkage with DR4 may contribute to disease expression.