In vitro human T cell responses to diphencyprone.

Abstract

The experimental contact sensitizer Diphencyprone (DPCP) is used both for topical immunotherapy and investigation of the human immune system. Analysis of mechanisms underlying altered immune responses requires in vitro systems. We have developed a method for detecting human T cell responses to DPCP in vitro. Twenty subjects were sensitized with DPCP (30?g/cm2) and 4 weeks later, were challenged with doses from 0.48 to 3.125?g. Responses at 48h showed all 20 were allergic. Peripheral blood mononuclear cells were cultured with a range of concentrations of DPCP for 6 days and proliferation quantified (3H thymidine uptake). The subjects were exposed repeatedly to DPCP (topical immunotherapy for warts or alopecia areata) or as repeated patch test challenges. Eight subjects gave positive lymphocyte proliferation responses (LPR), maximal responses being elicited with 16 or 32?M DPCP. Positive LPR became detectable from 20 weeks after sensitization and progressively more people become responsive over time to 40 weeks. The different time courses for manifestation of allergic reactivity in skin and blood probably reflects absence of memory T cells in blood due to their recruitment to skin as resident memory T cells. This assay can now be developed for analysis of components of the immune response.