Although the amounts of basal IL-17 secretion were not different between RA, OA and normal controls (62 ± 31, 43 ± 19 and 43 ± 10 pg/ml, respectively), the IL-17 production stimulated by PHA was significantly higher in RA PBMC than in those from OA and controls (768 ± 295 versus 463 ± 211 pg/ml [P < 0.05] and 241 ± 29 pg/ml [P < 0.001]). The gene discussed is IL17A; the disease is rheumatoid arthritis.