ORAL, PERIORAL AND SYSTEMIC PATHOSIS IN HGCL2-INDUCED AUTOIMMUNITY INTHE BN RAT

Male BN rats were repeatedly skin-injected with HgCl2 solution and sac rificed after 6, 9, 14, 21, 28 or 42 days. Mononuclear cell infiltrate s were observed in the oral mucosa and in lacrimal, salivary and thyro id glands from 6-9 days onwards, with a peak at 14-21 days. Immunohist ochemistry identified these cells as predominantly T cells with some N K cells but very few B cells. Reversible parenchymal changes were obse rved but there was no obvious persistent tissue destruction. Serum tit ers of IgE, IgG1, anti-laminin and anti-DNP, but not IgG2a antibodies, were raised and peaked at 14-21 days. However, there was no correlati on, within animals, between these titers and the extent of mononuclear cell infiltration. Mercury was histochemically detected within dendri tic cells/macrophages in the connective tissue stroma of the glands an d in the oral mucosa, but no correlation was found between the distrib ution of mercury and the degree of inflammation. We conclude that the accumulation of mononuclear cells in oral and perioral tissues of HgCl 2-treated BN rats does not represent a local immune response to tissue -retained Hg. Instead, we propose that the extravasation represents an epiphenomenon that is not necessarily deleterious to the infiltrated organ.