In vitro evaluation of the sensitization potential of weak contact allergens using langerhans-like dendritic cells and autologous T cells

Contact hypersensitivity is a major public health concern in most industria l countries, which is why predictive tests which could identify potential a llergens are needed. We have established an in vitro approach for the detec tion of primary immune response. This model uses Langerhans-like dendritic cells (LLDC) derived from cord blood progenitors and autologous T lymphocyt es, isolated from the same blood sample. Treatment of day 12-14 LLDC, with strong haptens trinitrobenzene sulfonic acid (TNP), fluorescein isothiocyan ate (FITC) or Bandrowski's base (BB), results in the proliferation of T lym phocytes, whereas weak allergens and irritants, such as sodium dodecyl sulf ate (SDS) are ineffective. The use of immature (day 8) LLDC and the additio n of a 48 h stage of incubation after hapten contact, result in phenotypic maturation of LLDC in addition to lymphocyte activation in all the cultures with strong haptens. The 48 h stage of incubation, results in sensitizatio n and in some cases the induction of T cell proliferation to citronellal (1 /8), coumarine (1/8) and to a prohapten p-phenylenediamine (pPDA; 2/8). The phenotype of DC after 48 h of contact with a strong hapten, becomes that o f mature DC (CD83(+), CD86(+) and HLA-DR++). With fragrance molecules, weak haptens and prohaptens, a comparable phenotype is observed only when T lym phocytes are activated. These data suggest that the unresponsiveness observ ed with weak haptens, may be the consequence on an incomplete maturation of LLDC. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.