Characteristics of tolerance induction among adult hapten-specific T lymphocyte precursors revealed by clonal analysis.

Thaptens 2,4,6-trinitrobenzene sulfonic acid (TNBS) and 3-iodo-4-hydroxy-5-nitrophenyl-acetic acid succinamide ester (NIP) on murine splenic and thymic cytotoxic T lymphocyte precursors (CTLp) was studied. Both BALB/c (H-2d) and CBA (H-2k) CTLp can be rendered unresponsive to subsequent in vitro stimulation with either hapten, provided the mice were pretreated with the correct dose of reactive hapten. The unresponsiveness was shown not to be due to toxicity, because treated animals can mount an alloreactive response equivalent to untreated animals. A degree of cross-reactivity in tolerance induction, however, was demonstrated between the two different haptens. Limit dilution analysis of tolerant lymphoid populations reveals that such cells obey single hit (zero order) kinetics and that there is effective deletion of the CTLp. After correction for "anti-self" responses, the anti-TNP CTLp frequency in TNBS-treated BALB/c mice was 10.7 X 10(-6) in contrast to 101.1 X 10(-6) in control animals (89.4% tolerance). Similarly, after correction for "anti-self" responses, the anti-NIP CTLp frequency in NIP-treated animals was 4.7 X 10(-6), in comparison to 42.8 X 10(-6) in control animals (89.0% tolerance). Kinetic studies show that tolerance occurs within 24 hr. This, together with the limit dilution data, argues against the role of suppressor cells, over the cellular range studied.