[Whether allergic contact dermatitis is necessary to induce systemic immunization by applied hapten]

Hapten specific lymphocyte proliferative assay was used to measure systemic immunization induced by epicutaneously applied hapten, instead of the assay measured by ear swelling or footpad swelling. DNFB was painted on the shaved back of C 57 BL/6 on two consecutive days and 4 days later. DNFB sensitized lymph node cells (LNC) were obtained from the regional lymph nodes. Spleen cells were pulsed with an antigen after irradiation and used as antigen presenting cells (APC). Various numbers of LNC were cultured with various number of APC to determine the highest lymphocyte proliferation. This was observed when 2 x 10(5) cells/well APC were cultured 4 x 10(5) cells/well LNC. In next step, this assay was used to investigate whether contact dermatitis is a required subject or not to sensitize. FB could not induce contact dermatitis on the painted region not only clinically but also histologically. FB, however, was able to induce hapten specific lymphocyte proliferation. This fact demonstrates that contact dermatitis is not always necessary in sensitization through epicutaneous application of hapten.