Dendritic cells and T cells transfer sensitization for delayed-type hypersensitivity after skin painting with contact sensitizer.

The cells involved in the development of delayed-type hypersensitivity (DTH) to the contact sensitizer fluorescein isothiocyanate (FITC) were examined. Cells used for transferring sensitization were obtained from donor mice up to 5 days following skin painting with FITC. Recipient mice were sensitized by footpad injections of dendritic cells (DC) obtained from donor lymph nodes up to 3 days following skin painting, when DC expressed high levels of antigen. DTH, assessed by ear swelling 24 hr following ear challenge with FITC, was detected when recipient mice were challenged 5 days after transfer of DC, but not when ear challenged immediately after transfer. Removal of donor DC using the cytotoxic antibody 33D1, plus complement, either from the DC-enriched population or from whole lymph node cells 24 hr after skin painting, abolished the capacity to transfer DTH. Purified T lymphocytes obtained from donor mice between Days 3 and 5 after skin painting, transferred DTH when recipients were ear challenged with FITC 5 days after footpad injections. DTH also occurred in mice ear challenged with antigen immediately after receiving footpad injections of either normal or irradiated T cells obtained from donors 4 days after skin painting. B cells and macrophages did not transfer sensitization for DTH throughout the time-course. Therefore an early stage in the immune response, where antigen-bearing DC initiated DTH, was distinguished from a later stage, where T cells transferred sensitization.