CD4 and systemic lupus erythematosus: Surprisingly, the levels of IL-17 in the culture supernatants were negligible even after the stimulation, and there was no significant difference in IL-17 levels between PBS- and Gal-9-treated MRL/lpr lupus-prone mice, suggesting that release of IL-17 was impaired in most CD4 T cells of MRL/lpr lupus-prone mice (Figure 3B).