Two distinct types of cellular mechanisms in the development of delayed hypersensitivity in mice: requirement of either mast cells or macrophages for elicitation of the response.

Using mast cell-deficient mutant W/Wv mice and their normal counterpart we re-evaluated the significance of participation of mast cells in allergic inflammatory response. W/Wv mice developed immediate hypersensitivity (IH) footpad reaction (FPR) to a somewhat lesser degree than the normal mice, suggesting that the mast cell might amplify the response. To exert classical tuberculin (tbc) delayed-type hypersensitivity (DTH) mast cells were not an essential cellular component. Vasoactive amines were essential to develop the response, but it did not necessarily originate from mast cells. When mice were immunized with methylated human serum albumin (MHSA) emulsified in incomplete Freund's adjuvant (IFA), mast cells were required to elicit DTH FPR. This was confirmed by the lack of the response in W/Wv mice, and the restoration of FPR by local transplantation of mature mast cells into mutant mice. This mast cell-dependent (MD) DTH was different from tbc DTH as follows: mast cell dependency, macrophage dependency as revealed by ferritin sensitivity, kinetics of sensitization, effect of host's age and histopathology. Thus we concluded that there are two types of DTH in mice; one is macrophage-dependent tbc and the other is mast cell-dependent DTH. The correspondence of the DTH to the Jones-Mote (JM) DTH is discussed, although the dominance of mast cells in MD DTH lesion was not observed.