Delayed type hypersensitivity to allogeneic cells in mice. I. Requirements for optimal sensitization and definition of the response.

Mice were sensitized to allogeneic cells under defined conditions, and their response to antigen deposition in the ear was measured by the influx of radioisotope-labeled cells. The delayed onset, T cell dependency and histology of the ear reaction were characteristic of delayed type hypersensitivity (DTH). Positive responses were obtained in a strain combination unable to elicit a mixed lymphocyte reaction (MLR), in B-Ly mice incapable of cytotoxic T lymphocyte (CTL) generation and in allogeneic combinations challenged with noncellular material. This suggests that MLR and CTL cannot, on their own, account for the response. Hence the ear reaction can best be explained in terms of DTH.