Delayed hypersensitivity to mono-azobenzene arsonate-N-acetyl-L-tyrosine. II. An operational model in the mouse.

Immunization of the mouse by free mono-ABA-Tyrosine (ABA-Tyr) in complete Freund's adjuvant leads to a specific sensitization. This can be assessed by increase in ear thickness after challenge with ABA-Protein conjugates. The intensity of the skin reaction is directly related to both the antigen dosage and the amount of BCG incorporated in the adjuvant. A close correlation has been shown between delayed skin reaction and "in vitro" lymphocyte proliferation in the presence of either ABA-Protein or free ABA-Tyr. In both "in vivo" and "in vitro" tests, sensitization is detectable from day 5 with a maximum on day 7. Contrasting with this strong cellular response, no antibody can be found. Thus, mouse sensitization with ABA-Tyr provides an operational model for pure cellular immunity. The extension of ABA-Tyr model to mouse may vacilitate the analysis of the involved cell populations.