Pathologic analysis of contact hypersensitivity.

Ears were harvested 24 hours after secondary oxazolone challenge. (A) Wild-type mouse, diluent only. (B) Sensitized wild-type mouse, hapten challenge. (C) Sensitized GM-CSF/IL-3–deficient mouse, hapten challenge. (D) Sensitized GM-CSF/IL-3–deficient mouse plus control treatment, hapten challenge. (E) Sensitized GM-CSF/IL-3-deficient mouse plus GM-CSF/IL-3 treatment, hapten challenge. All panels at ×200.