Induction of immunological memory in the skin. Role of local T cell retention.

Using an experimental contact sensitivity model in guinea-pigs, evidence is presented that hapten (DNCB or oxazolone) specific T lymphocytes may persist for several months in previous sites of inflammation. Immunological memory, revealed by accelerated contact skin reactions upon retesting with the hapten, was limited to the original contact skin reaction sites. This 'local skin memory' to DNCB or oxazolone could be induced in both specific and non-specific skin inflammatory reactions, provided the animals had been sensitized to the hapten not longer than 2 weeks before. In animals which had been sensitized more than 1 month earlier, local skin memory could be induced if the animals received a booster application of hapten shortly (0-2 days) before primary skin testing. From these results we conclude that recently activated T cells may enter inflammatory sites non-specifically, producing specific local immunological memory. This memory may last several months. Accumulation of hapten specific T cells at inflammatory sites may be important in retest reactivity, in flare-up reactivity and in chronic inflammation.