Analysis of lymphocyte phenotype and T cell receptor genotype in Felty's syndrome.

Natural killer (NK) cells and CD3+ large granular lymphocytes (LGL) were investigated in patients with Felty's syndrome (FS), rheumatoid arthritis (RA) and healthy controls. In most patients with FS, NK cell number and activity were decreased. CD3+ LGL were unchanged. However, in one patient a marked expansion of CD3- CD16+ CD56+ (NK) cells was seen and in a second, an expansion of CD3+ LGL. In FS there was also an increase in HLA- DR+ and CD8+ but not gamma delta+ T cells. Three of 11 patients with FS studied demonstrated a dominant rearrangement of the T cell receptor beta gene constant region consistent with oligoclonal T cell expansion.