Patch test is an allergic contact dermatitis in miniature. The purpose of this study is to throw light on the pathogenesis of allergic contact dermatitis (AGO). One-hundred subjects were included in this study (30 with cement dermatitis, 30 with nickel dermatitis and 40 as healthy controls). Biopsies of these patients were examined with the use of monoclonal antibodies against T-cell subsets (CD3, C04, C08) and Langerhans cells (CD6). Eight selected patients were examined by electron microscopy. Our results regarding immunological study showed that the majority of T-cells were CD4 (+ve) cells (helper / inducer) mainly detected in the reticular dermis while the minority were CD8 (+ye) cells (suppressor - cyfotoxic) mainly detected in the papillary dermis. There were increase, in the density of CD6 (we) cells in both cement and nickel dermatitis at 6 hours diopsy. C06 (-we) cells gradually decreased with increasing time of allergen. Electron microscopic examination at 6 hours after allergen application revealed intercellular and infracellular oedema which were prominent in basal keratinocytes. Keratinocytes showed signs of damage in the form of swollen mitochondria, intracytoplasmic vacuolation and sparse chromatin. These signs of damage gradually increased with increasing time of patch test at 12, 24 and 48 hours after allergen application. These results indicate that with chronicity of disease, CO3, CD4 and CD6 (-i-va) cells decreased while COB (+ve) cells were increased confirming the role of cell mediated immunity in the pathogenesis of ACD. Also, these results indicate that degenerative changes of keratinocytes were due to Langerhans dependent cellular cytotoxicity. |
