CD4 and acne: We and others revealed that C. acnes induce IL-17 and IFN-γ in CD4+ T cells, and that IL-17-secreting cells are visualized within the perifollicular infiltrates of acne lesions, which is consistent with the fact that TH17 cells may contribute to both the inflammatory and/or antimicrobial responses during acne progression (4, 52, 100).