SPECIFIC STABILIZATION OF THE 4F7 MOLECULE ON DENDRITIC CELLS BY CONTACT ALLERGENS

Our laboratory has recently developed the monoclonal antibody 4F7 whic h recognizes a molecule on dendritic cells in the dermis of mice that is upregulated after application of contact allergens in vivo, Further more, this antibody detects an antigen on dendritic cells in spleen, l ymph nodes and colon, In order to study the influence of contact aller gens on the surface expression of the 4F7 molecules on dendritic cells , FACScan analysis of splenic dendritic cells was carried out after in vitro application of contact allergens, Freshly isolated splenic dend ritic cells were found to be positive for 4F7, 33D1, N418 (CD11c) and MHC class II. After overnight culture the expression of the dendritic cell-specific molecules 4F7 and 33D1 was decreased, This downregulatio n was not inhibited by the addition of the cytokines TNF-alpha or GM-C SF during in vitro culture. However, in vitro treatment of freshly iso lated dendritic cells with the contact allergen 2,4-dinitrofluorobenze ne prevented this downregulation of the 4F7 surface molecules. The sam e effect was observed after treatment with other contact allergens (1- chloro-2,4-dinitrobenzene or potassium dichromate), Treatment with the irritant substance sodium dodecyl sulphate, the lectins concanavalin and lipopolysaccharide or the phorbol ester PMA did not prevent the do wnregulation of 4F7 and 33D1, Moreover, the influence of contact aller gens on the expression of the molecules 4F7 and 33D1 was not inhibited by the protein synthesis inhibitor cycloheximide. No effects of conta ct sensitizers were detectable on the expression of MHC class II molec ules or the costimulatory molecules B7 and heat-stable antigen, Our re sults show a specific stabilizing effect of contact allergens on the d endritic cell-specific molecules 4F7 and 33D1 independent of de novo p rotein synthesis.