Felty's syndrome associated with high levels of IgA rheumatoid factor

Felty's and pseudo-Felty's syndromes

Felty's syndrome, consisting of rheumatoid arthritis, leukopenia, and splenomegaly, has been recognized as a distinct clinical entity for more than 60 years. Clinical and laboratory manifestations of the condition are reviewed. The major sources of morbidity and mortality remain recurrent local and systemic infections. Immunogenetic analysis shows a strong association with HLA-DR4, in addition to DQ beta 3b and C4B null allele. Potential mechanisms of neutropenia are contrasted, including impaired granulopoiesis and neutrophil-immune complex interactions. Lithium carbonate and splenectomy may have a role in the treatment of fulminant disease. Maintenance therapy should be directed at control of the underlying inflammatory arthropathy. A syndrome of proliferation of large granular lymphocytes and neutropenia, associated with rheumatoid arthritis in 23% to 39% of cases, has been described recently. Cases of "pseudo-Felty's" syndrome are often confused with traditional Felty's syndrome, which has twice the prevalence. The clinical and laboratory distinctions between these two conditions are elaborated.

Quantitation of rheumatoid factors (RF) of IgM, IgA and IgG isotypes by a simple and sensitive ELISA. Discrimination between false and true IgG-RF

An enzyme-linked immuno-sorbent assay (ELISA) for quantitation of rheumatoid factors (RF) of IgM, IgA and IgG isotypes has been established. A complex of human serum albumin (HSA) and rabbit IgG anti-HSA antibodies is used as antigen for RF. The binding of RF is detected by stepwise additions of biotinylated monoclonal antibodies specific for human IgM, IgG or IgA, alkaline phosphatase-conjugated streptavidin, and substrate. The assay is simple and applicable to routine testing of large numbers of sera. It discriminates between false and true IgG-RF by papain digestion of sera that turn out positive by the screening for IgG-RF. Of 241 randomly selected patients with rheumatoid arthritis (RA) as well as other rheumatoid and infectious diseases, 110 were Waaler-Rose-positive while 127 were IgM-RF-positive in ELISA. The correlation between the Waaler-Rose test and IgM-RF ELISA was highly significant (r = 0.82). By testing 65 of these sera (all IgM-RF positive), 25 (39%) were also true IgG-RF positive (42 (64%) in the screening). When 40 Waaler-Rose-positive RA patients were tested, 20 and 21 were also positive for IgG- and IgA-RF, respectively. Eight IgM-, one IgA- and no IgG-RF positive tests were recovered when 48 Waaler-Rose negative RA patients were studied.

Prospective study of early rheumatoid arthritis. II. Association of rheumatoid factor isotypes with fluctuations in disease activity

Thirty-three patients with early peripheral synovitis were followed up for two to four years in order to study the relationship between fluctuations in rheumatoid factor (RF) levels and indices of clinical activity. Twenty-eight of these patients developed classical/definite rheumatoid arthritis (RA). Seventeen patients developed erosive disease of their hands and wrists and thirteen had a positive RF agglutination test. Nineteen patients had raised levels of IgM, RF, IgA, RF, or IgG RF as measured by isotype-specific ELISA techniques. The within-patient fluctuations in IgA RF levels correlated significantly with the corresponding fluctuations in grip strength (p less than 0.05), erythrocyte sedimentation rate (ESR) (p less than 0.01), and a composite index of disease activity (p less than 0.02). IgG RF levels were also associated with changes in ESR and grip strength, but IgM RF showed only a weak association with fluctuations in ESR and not with any other clinical parameters. It is suggested that serum IgA RF may be a useful marker of disease activity in rheumatoid arthritis.