Impaired TNCB-specific DTHRs in TNFR1^−/− mice. (A) TNCB-sensitized and naive TNFR1^−/− () and TNFR1^+/+ (■) mice were challenged with TNCB. Ear thickness was measured before and at the indicated time points after TNCB challenge. Differences in ear thickness between TNFR1^−/− () and TNFR1^+/+ (■) were significant (P < .05) 24, 48, and 72 hours after ear challenge (24 hours: n = 16-27; 48 hours and 72 hours: n = 6 or 7). (B) Reduced PMN infiltrates, tissue necrosis, and edema in ear tissue from TNFR1^−/− mice 24 hours after TNCB challenge. Hematoxylin and eosin–stained ear sections from TNFR1^+/+ (left: top represents overview; bottom represents detail) and TNFR1^−/− mice (right: top represents overview; bottom represents detail; n = 13-15). (C) PMN recruitment is TNFR1-dependent. MPO activity in protein extracts from ear tissue from TNFR1^−/− and TNFR1^+/+ mice (n = 3).