Hapten-specific prophylaxis of murine contact sensitivity by DNP-amino acid derivatives

In mice, the elicitation of DNFB contact skin reaction was suppressed by the intravenous injection of relatively small amounts of DNP-amino acid conjugates when given at the same time of challenge test. Maximal suppression achieved was around 70% when optimal doses of DNP-amino acid were administered. The suppressive activity of 4 different amino acids, i.e., DNP-L-lysine, DNP-S-cysteine, DNP-alanine, and DNP-glycine, was nearly the same, respectively. This inhibitory effect was hapten-specific, and it failed to suppress the strong skin reaction elicited in cyclophosphamide-pretreated mice. Using the lymphocyte culture system, low doses of DNP-amino acid also suppressed the antigen-specific proliferation of sensitized lymph node cells (T prlf). Preincubation of sensitized cells with DNP-amino acid eliminated the transfer activity of T-DH cells as demonstrated previously. The mixture of lymph node cells and spleen cells from DNP-L-lysine-treated mice in vivo also suppressed the elicitation of skin reaction when transferred to recipient mice sensitized 5 days previously. Transfer studies demonstrated that this suppression was mediated by Lyt 1.2 (+), Thy 1.2 positive cells in vivo.