Inhibition of oxazolone-induced ear swelling in sensitized mice. Mice were sensitized to oxazolone and rechallenged by topical treatment of one ear (see Methods). Swelling was measured by ear thickness, and the value obtained from the vehicle-treated control ear was subtracted from those obtained from oxazolone-treated mice. (a) Animals received a single intravenous injection of heparin (1 mg), heparin derivative (1 mg), or saline within 30 minutes after antigen challenge. *Significant difference in ear swelling in the control mice injected with saline (gray bar) versus those that were injected with the heparin derivatives (black bars). (b) Sensitized wild-type and selectin-deficient mice were injected with heparin (1 mg) and rechallenged with antigen as in a. Each bar represents the average value ± SD; n = 5–8. *Significant difference in ear swelling in mice treated with heparin (black bars) versus control mice that received only saline (gray bars).