Effect of intradermal injections of CPAF, LTA, or PDG on skin inflammation. The dorsal sides of ears of wild-type and PAF-R^–/– mice were injected with 100 ng CPAF, 10 μg LTA, 10 μg PDG (wild-type mice only), or 2.0 mg histamine in 1 ear and BSA vehicle control on the other. After 2 hours, 5-mm punch biopsies were performed and tissues weighed, and the differences in ear biopsy specimen weights between CPAF/LTA versus BSA vehicle assessed. (A) Intradermal injection of CPAF or LTA induced local cutaneous inflammation (as measured by increased tissue weight) in wild-type but not PAF-R^–/– mice. The data consist of the mean ± SD of the difference between LTA/PDG/CPAF/histamine and vehicle-injected ear biopsy specimen weights using 6–7 mice in each group. *Statistically significant (P < 0.05) difference in ear thickness between WT and PAF-R^–/– mice. (B) Representative H&E-stained sections from CPAF-, LTA-, histamine-, or vehicle control–injected ear biopsy specimens revealed significant edema with scattered neutrophils and a few eosinophils in the skin of wild-type mice after intradermal injection of CPAF or LTA compared with essentially no effect on the ear skin of PAF-R^–/– mice. Both wild-type and PAF-R^–/– mice were equally responsive to intradermal injection of histamine as positive control. CON, control. Magnification, ×100.