The results shown in Figs. 1a, 1b, and 1c indicate that skin antimicrobial peptides (a, murine peptides; b and c, human peptides) are very important in the resistance of mice to P. aeruginosa i.d. infections, and CD31+ IMC are responsible for inhibiting HBD-1 production by skin tissues. This evidence concerns the gene PECAM1 and infection.