Abstract
There is a need to develop methods to evaluate the sensitization potential of chemicals and/or materials that contact breached skin (e.g. polymeric tissue adhesives, wound dressings, occupational exposure to chemicals through wounded or irritated skin). For this purpose a modified local lymph node assay (LLNA) was conducted using standardized methods for breaching the skin at the dose application site. Female BALB/C mice were exposed for three consecutive days on the ear to vehicle (.9% sterle saline) or a foreign protein (25% human albumin) via the topical route, breached skin route utilizing either a Simplate (Organon Teknika, Corp., Durham, NC) or a Multi-Test (Lincoln Diagnostics, Inc., Decature, IL) device, or injected in the subcutaneous tissue between the ears. In order to investigate the potential for enhanced sensitivity of the assay by occlusion, for each test condition (excluding the subcutaneous group) the exposure site was occluded using Blenderm (3m Corp., St. Paul, MN) tape in one group of animals and left unoccluded in a second group. Two days following the final exposure animals were injected intravenously with 311 thymidine, sacrificed five hours later and the draining lymph nodes excised and processed as for a standard LLNA. When unoccluded, no difference in proliferation occurred following topical application to intact skin. However, an increased proliferative response (>5 fold) was seen following both methods of breached skin with no significant differences between methods. With occlusion, exposure by all routes induced significant proliferation, however breaching with the Multi-Test device induced significantly higher (>3 fold over topical and >2 fold over Simplate) proliferation than by the other routes and induced proliferation similar to that observed following subcutaneous administration. Results indicate that the Multi-Test may provide a useful method for breaching the skin in testing compounds where exposure is anticipated to occur compromised skin.