Immunocytochemical analysis of early focal cellular infiltrates in experimental oral contact hypersensitivity.
Warfvinge G, Larsson A
The cellular infiltrates of early contact hypersensitivity reactions to 2,4-dinitrofluorobenzene (DNFB) in rat oral mucosa were phenotypically characterized using serial frozen tissue sections and monoclonal antibodies. CD2+CD45RB- lymphocytes and ED1+RT1B/D+ monocytes/macrophages appeared in focal collections at the epithelium-connective tissue interface 2-6 h after challenge with DNFB. These foci also contained CD4+, CD5+, CD8+, TCR alpha beta+ cells. CD45RB+ "naive" T cells were difficult to detect at 2-6 h but appeared in significant numbers at 24 h post-challenge. At this stage, the number of all the other phenotypes also was increased. CD2+ cells were approximately twice as many as CD5+ or TCR alpha beta+ respectively, indicating that TCR gamma delta+ lymphocytes might be involved. An additional observation was the presence of increased numbers of CD2+ lymphocytes in the oral mucosa of sensitized but not challenged animals. Our findings indicate that the oral mucosa of skin DNFB pre-sensitized animals may be "contact hypersensitivity conditioned" by migration-prone memory T cells, and that these cells may rapidly interact with locally resident epithelial Langerhans' cells following antigen restimulation, creating the very initial antigen-specific part of experimental oral contact hypersensitivity.