Employing normal PB (1.7 ± 0.3%) or RA PB (2.1 ± 0.6%), pretreatment with IL-23 did not increase the number of TH-17 cells compared with P/I alone; however, the percentage of TH-17 cells was significantly higher than in the untreated group. The gene discussed is IL23A; the disease is rheumatoid arthritis.