Diminished croton oil-induced acute inflammation in mast cell deficient (W/W/sup v/ and S1/S1/sup d/) mice

Mast cells (MC) have been implicated in the pathogenesis of acute inflammatory reactions. The authors tested the response of WBB6F1-W/W/sup v/ and WCB6F1-S1/S1/sup d/ mice, and their normal (+/+) littermates to croton oil (C.O.), an agent which induces an acute inflammatory response in the mouse. Mice received C.O. (200 μg) topically to the left (L) ear and vehicle alone to the right (R) (control) ear. Ear weight ratios (L/R, an indicator of swelling), 125I-5-iodo-2-deoxyuridine (125I-IUDR)-labeled leukocyte infiltration ratios and histology (1+m) Epon sections) were examined 6-18 hr after challenge. The authors found: 1) a significant diminution in the ear weight and 125I-IUDR ratios in W/W/sup v/ and S1/S1/sup d/ mice as compared to congenic +/+ mice, 2) histologic evidence of diminished neutrophil infiltration in reactions to C.O. in W/W/sup v/ and S1/S1/sup d/ mice, and 3) evidence of MC activation in C.O. reactions in +/+ mice. Topical C.O. had little or no effect on peripheral blood leukocyte counts. The C.O. response of W/W/sup v/ mice whose tissue MC were restored by transplantation of congenic +/+ bone marrow resembled that of +/+ mice. These data are consistent with a role of mast cells in augmenting the acute inflammatory response to epicutaneous croton oil in the mouse