Delayed-type skin reaction to 2,4-dinitrophenylated epidermal cells in guinea pigs with contact sensitivity to 2,4-dinitrochlorobenzene.

Contact sensitivity (CS) induced by hapten has been thought to be analogous to delayed-type hypersensitivity, such as the Mantoux reaction, because of outstanding similarities between the two phenomena. It can be suggested that animals with CS respond also to intradermal injection of the conjugate of hapten and protein as well as to epicutaneous application of hapten. However, evidence against this has been reported. In the present experiments, delayed-type skin reaction (DSR) was successfully obtained in JY1 strain guinea pigs sensitized by painting the skin with 2,4-dinitrochlorobenzene using in vitro dinitrophenylated epidermal cell suspension (DNP-EC) as antigen for a delayed intradermal test. The experiment using anti-Ia alloantiserum and complement showed that the elicitation of DSR is due to the presence of Ia-positive cells (presumably Langerhans cells) among DNP-ECs. The delayed intradermal test with the conjugates such as haptenated ECs in the animals with CS is considered to be an experimentally useful way of analysing the antigen in the sensitivity.