Neutrophil surface-bound immunoglobulin--a feature of Felty's syndrome?

In a study of eight patients with Felty's syndrome, surface-bound immunoglobulin (IgG +/- IgM and complement) was demonstrated in all cases by a fluorescein-labelled antihuman globulin technique using paraformaldehyde-fixed neutrophils to prevent non-specific surface adsorption of immunoglobulin. The test was negative in control patients with rheumatoid arthritis alone. The neutrophil binding of immunoglobulin occurred in vivo and could not be reproduced with the patient's serum and normal neutrophils. The presence of alloantibodies due to previous pregnancy or transfusion can obscure this picture. A neutrophil autoantibody or cell-bound immune complexes may be the cause of this phenomenon, which may be a useful marker of Felty's syndrome in patients with rheumatoid arthritis.