To study the importance of S. aureus Lpp and the influence of TLR2 deficiency on the severity and frequency of clinical arthritis, wild-type (WT) and TLR2 deficient (TLR2−/−) mice were intravenously inoculated with an arthritic dose of either S. aureus Newman parental strain expressing Lpp (WT/Newman and TLR2−/−/Newman, respectively) or S. aureus NewmanΔlgt mutant strain (WT/Δlgt and TLR2−/−/Δlgt, respectively). This evidence concerns the gene TLR2 and Arthritis.