Application of HEMA on intact mouse skin--effects on the immune system

Previously, we have shown that 2-hydroxyethylmethacrylate (HEMA) can bind to protein and that autoantibodies were induced in mice by immunization with a self-protein in vitro conjugated with HEMA. The present study aimed to develop a model for HEMA-induced sensitivity by the application of the substance on intact skin. Female BALB/c mice were painted on the dorsum of each ear with 50% HEMA in vehicle twice a week for 6 weeks. The anti-CD3epsilon-stimulated lymph node production and the spontaneous spleen-cell production of the cytokines interleukin (IL)-2, IL-4, IL-6, IL-10 and interferon-gamma were assessed by enzyme-linked immunosorbent assay. In another experiment, the cytokines were followed after subcutaneous HEMA injections. Animals painted with HEMA had a significantly higher IL-6 production by anti-CD3epsilon-stimulated lymph node cells and significantly suppressed IL-10 production by spleen cells compared to vehicle-treated mice. This correlated to some extent with the spontaneous spleen-cell production induced by subcutaneously administered HEMA. An injection of 20 micromol of HEMA induced an increased production of IL-6, while injection of 40 micromol depressed both IL-6 and IL-10 production. Although there was no sign of inflammation on the ears, findings suggest that HEMA had penetrated the skin and induced a reaction in the immune system.