Histological study on the fate of haptenated epidermal cells injected intradermally in guinea pigs.

The percutaneous administration of in vitro haptenated epidermal cells (EC) has become established as a procedure to produce contact sensitivity (CS) in experimental animals for routine use. The cells have also been found to elicit a significant delayed-type skin reaction by intradermal test in the animals sensitized by painting the skin with the hapten. The fate of 2,4-dinitrophenylated (DNP) isogeneic epidermal cell suspensions (EC) injected intradermally was investigated histologically in intact or 2,4-dinitrochlorobenzene (DNCB)-sensitized strain 13 guinea pigs to study the role of the cells in CS. DNP-EC were found to proliferate actively in the dermis and formed EC nests with central keratinization and then elicited inflammatory reaction associated with necrosis of the epidermal structures 7 days after injection in the intact animals. DNP-EC injected intradermally into the animals which had received and reacted against DNCB underwent a suppression of EC proliferation. These findings are discussed in relation to the role of the haptenated EC in CS.