A PLASMACYTOID DENDRITIC CELL (CD123+/CD11c−) BASED ASSAY SYSTEM TO PREDICT CONTACT ALLERGENICITY OF CHEMICALS.

This study by scientists at MatTek Corp. demonstrated that CD86 expression in the plasmacytoid Dendritic Cell (pDC) fraction of MatTek’s Human Dendritic Cells is a sensitive and specific indicator of contact allergenicity, and that an assay method utilizing normal human plasmacytoid dendritic cells will be useful for high throughput screening of chemicals for allergenicity. A predictive allergenicity test system for assessing the contact allergenicity of chemicals is needed by the cosmetic and pharmaceutical industry to monitor product safety in the marketplace. Development of such non-animal alternative assay systems for skin sensitization and hazard identification has been pursued by policy makers and regulatory agencies. MatTek scientists investigated whether phenotypic and functional changes to a subset of dendritic cells (DC), plasmacytoid DC (pDC), could be used to identify contact allergens. To achieve this goal, normal human DC were generated from CD34+ progenitor cells and cryopreserved. Frozen dendritic cells were thawed and the pDC fraction (CD123+/CD11c−) was harvested using FACS sorting. The pDC were cultured, expanded, and exposed to chemical allergens (N = 26) or non-allergens (N = 22). Concentrations of each chemical that resulted in >50% viability was determined using FACS analysis of propidium iodide stained cells using pDC from 2 to 5 donors. Expression of the surface marker, CD86, which has been implicated in dendritic cell maturation, was used as a marker of allergenicity. CD86 expression increased (¡Ý1.5-fold) for 25 of 26 allergens (sensitivity = 96%) but did not increase for 19 of 22 non-allergens (specificity = 86%). In a direct comparison to historical data for the regulatory approved, mouse local lymph node assay (LLNA) for 23 allergens and 22 non-allergens, the pDC method had sensitivity and specificity of 96% and 86%, respectively, while the sensitivity and specificity of the LLNA assay was 83% and 82%, respectively. In conclusion, CD86 expression in pDC appears to be a sensitive and specific indicator to identify contact allergenicity. Such an assay method utilizing normal human cells will be useful for high throughput screening of chemicals for allergenicity.

Allergenicity, Allergens, Balsam of Peru, Birbeck granules, CD1a, CD34+ progenitor cells, CD80, CD83, CD86, Contact allergenicity, Dendritic cells, HLR-DR, Hazard identification, Langerhans cells, Lymph node assay (LLNA), Myeloid DC, Non-allergens, Plasmacytoid dendritic cells, Skin sensitization, Tween 20, pDC

5-Methyl 2,3 hexanedione, Aluminum chloride, Ammonium hexachloroplatinate (HCPt), Bandowski's base, Benzalkonium chloride, Benzoyl chloride, Beryllium sulfate, Chloramine-T, Chlorobenzene, Chlorpromazine, Cinnamaldehyde, Cobalt chloride, Dimethyl sulfoxide, Dinitrochlorobenzene, Dinitrochlorobenzene sulfonic acid, Diphenylmethane diisocyanate, Ethanol, Ethylene glycol dimethacrylate, Fluorescein isothiocyanate, Glutaraldehyde, Glycerol, Hexane, Hydrocortisone, Hydroquinone, Isopropanol, Kanamycin, Lead acetate, Manganese chloride, Neomycin sulfate, Nickel chloride, Nickel sulfate, Nonanoic acid, Penicillin G, Phenol, Phenyl benzoate, Potassium dichromate, Potassium hydroxide, Propyl gallate, Propylene glycol, Pyridine, Salicylic acid, Sodium lauryl sulfate, Tartaric acid, Tetramethylthiuram disulfide, Tween 80, Xylene, Zinc sulfate, p-Phenylene diamine