PLASMACYTOID DENDRITIC CELLS AS A TOOL FOR TESTING ALLERGENICITY OF CHEMICALS.

This study by MatTek Corp. scientists demonstrated that MatTek’s Human Dendritic Cells (DCs) contain both plasmacytoid DCs (pDC) and myeloid DCs (mDC), that they can be separated into those 2 cell populations, and that MatTek pDCs can be used to differentiate between allergens and irritants with a high degree of sensitivity (92-94%) and specificity (93-100%). A predictive test system for assessing the allergenicity potential of chemicals will have enormous significance in industries involved in cosmetic, personal hygiene and topical medication products and in the fields of dermatology and immunology. Since dendritic cells/Langerhans cells (DC/LC) are the first cells responsible for sampling skin and mucosal surfaces for changes in the antigen microenvironment, MatTek investigated whether phenotypic and functional changes to a subset of DC, plasmacytoid dendritic cells (pDC), could be used to identify allergens. To achieve this goal, MatTek generated normal Human Dendritic Cells were from CD34+ progenitor cells and were cryopreserved. Frozen DC were thawed and the pDC fraction (CD123+/CD11c-) was collected using FACS sorting. The pDC were cultured, expanded, and pulsed with chemical allergens (n=13) or irritants (n=7). Sub-toxic concentrations of each chemical was determined using FACS analysis on propidium iodide stained cells. Concentrations that resulted in >75% cell viability were used in the study. Results showed that exposure of pDC (n=3-5 donors) to allergens induced an increase (¡Ý1.5 fold) in surface expression of CD86 for 12 of the 12 allergens and one of three donors was positive for the 13th allergen; on the other hand, 5 of 7 non-allergens (irritants) did not result in increased CD86 expression when tested against multiple donors (N=4-5 donors). Based on these findings, MatTek developed a prediction model with a sensitivity of 92-100%, specificity of 77-88%, and an accuracy of 86%. Increased levels of released IL-6 were also detected in culture supernatants of allergen-pulsed pDC (6 of 6), but not from cultures of non-allergen-treated pDC. In conclusion, MatTek has established that the use of CD86 expression on pDC appears to be a sensitive and specific predictor of allergenicity of chemicals. When compared with existing animal models, the assay MatTek has developed is advantageous because high throughput screening of chemicals using cells of human origin is possible at low cost.

Allergen-pulsed pDC, Allergenicity, Allergenicity potential of chemicals, Allergens, Antigen microenvironment, CD1a, CD34+ progenitor cells, CD86, CS123+/CD11c-, Chemical allergens, Co-stimulatory molecules, Dendritic cells, HLA-DR, IL-12 (p40), IL-6, Irritants, Langerhans cells, Mucosal surfaces, Plasmacytoid dendritic cells, Prediction model, Predictive test system, Surface marker expression, pDC, pDC fraction (CD123+/CD11c-)

Balsam of Peru, Bandowski¡¯s Base, Cinnamaldehyde, Cobalt chloride, DMSO, Dinitrocholorobenzene, Dinnitrobenzene sulfonic acid, Ethanol, Fluorescein isothiocyanate, Gllutaraldehyde, Hydroquinone, LPS, Neomycin sulfate, Nickel sulfate, P-phenylene diamine, PBS, Potassium dichromate, Potassium hydroxide, Propylene glycol, Sodium dodecyl sulfate, TNF-a, Tween-20