IL17A and psoriasis 14, pustular: In contrast, the serum concentrations of IL-17 were higher in the psoriasis group compared to the healthy group (P < 0.001; Table 4), which decreased in the following order: PV < PA < EP, whereas the difference in IL-17 between the GPP patients and the healthy group was not significant (P > 0.05; Fig. 2b).