TLR2, but not TLR4, TLR6, or TLR1, is sufficient for induction by P. acnes of monocyte activation. a, HEK 293 cells transfected with TLR2, CD14, and the NF-κB responsive E-selectin (ELAM) enhancer luciferase reporter gene and BaF3 cells stably expressing TLR4, CD14, MD-2, and an ELAM luciferase reporter gene were activated with P. acnes, M. tuberculosis 19-kDa lipoprotein, or LPS for 6 h. NF-κB activity was measured by luciferase assay. Data reflect at least two independent experiments. b, Peritoneal macrophages were obtained from wild-type, TLR2−/−, and TLR6−/− mice, activated with P. acnes, and supernatants were assayed for the presence of IL-6. c, Peritoneal macrophages were obtained from wild-type and TLR1−/− mice, activated with P. acnes, and supernatants were assayed for the presence of IL-6.