Phenotypic characterization of human CD4(+) regulatory T cells obtained from cutaneous dinitrochlorobenzene-induced delayed type hypersensitivity reactions

In this study, we describe the generation and characterization of cloned hu man CD4(+) T lymphocyte populations that have infiltrated into cutaneous, 2 ,4-dinitrochlorobenzene-induced delayed type hypersensitivity reactions in healthy human subjects. It is shown that, in addition to T helper type 1 cl ones, elevated numbers of regulatory T clones, producing high levels of int erleukin-10 and interleukin-5, but no measurable interleukin-4, were isolat ed from delayed type hypersensitivity reactions in four of six donors. A su bsequent challenge with 2,4-dinitrochlorobenzene of two donors from whom on ly few interleukin-10-producing T cell clones had been generated after prim ary challenge, resulted in a decrease in the frequency of T helper type 1 c lones and a strong increase in the number of interleukin-10-producing T hel per type 2 and regulatory T clones. Culture supernatants from the latter ce lls, activated with anti-CD3 and anti-CD28 monoclonal antibody, inhibited a lloantigen-mediated T cell proliferation which was, partly dependent on int erleukin-10, and independent of transforming growth factor-beta. In additio n, dendritic cells generated in vitro in the presence of these culture supe rnatants were impaired in their ability to induce alloantigen-induced proli ferative responses. Differential expression of transcripts for the T1/ST2 m olecule enabled a phenotypic distinction between resting regulatory T cells and T helper type 2 cells, but not between regulatory T cells and T helper type 1 cells. This experimental model provides a useful tool to isolate hu man inflammatory and anti-inflammatory T cell subpopulations and, furthermo re, enables the study of the kinetics of their appearance into delayed type hypersensitivity reactions.