Responses of P1’s and P2’s fibroblasts to IL-17 cytokines. (A and B) IL-6 (A) and GRO-α (B) production by SV40-immortalized fibroblasts from controls, P1 (IL-17RC Q138*/Q138*), P2 (IL-17RC Q376*/Q376*), and an IL-17RA–deficient patient (IL-17RA Q284*/Q284*), after 24 h of stimulation with IL-17A (10 and 100 ng/ml), IL-17F (10 and 100 ng/ml), and IL-17A/IL-17F (10 and 100 ng/ml), as determined by ELISA on supernatants. Means ± SD (error bars) of three independent experiments are shown. Statistical analyses were performed by the nonparametric statistical test (Mann–Whitney test), comparing NS (nonstimulated) and activated samples (*, P < 0.05; **, P < 0.01). The experiments were repeated at least three times.