P. acnes and S. epidermidis added to the medium of reconstructed human epidermal equivalents induce dose-dependent proinflammatory and cytotoxic reactions. After 24 hrs incubation with bacteria at 1 × 107, 1 × 108 and 1 × 109 CFU, the interleukin (IL)-1α (A), IL-8 (B) and TNFα (C) levels in the RHE growth medium were measured. The cell viability (D) was assessed by measuring leakage of cytoplasmic Lactate Dehydrogenase (LDH) into the RHE growth medium. Data are expressed as percentage of untreated control (UnC = 100%) and are presented as mean ± one standard deviation. Single and double asterisks indicate statistically significant differences (P < 0.05 and P < 0.01) versus the untreated control.