Induction of sensitization and tolerance in contact sensitivity with haptenated epidermal cells in the guinea-pig

Haptenated murine Langerhans' cells (LCs) have been reported to induce contact sensitivity when injected via the subcutaneous, intraperitoneal and, in some instances, the intravenous route. Similar studies were undertaken to elucidate the role of the LC in the induction of contact sensitivity in the guinea-pig. The subcutaneous injection of dinitrophenylated epidermal cells induced hapten-specific contact sensitivity in a dose-dependent fashion. This contrasts with the tolerance that was induced by the intravenous or intraperitoneal injection of similarly haptenated cells. Contact sensitivity by haptenated epidermal cells could be induced in syngeneic and allogeneic recipients and did not require the transfer of viable cells. Using the monoclonal antibody MSgp2, which detects LCs, LC-enriched and LC-depleted populations were prepared by an 'indirect antibody' panning technique. It was found that a haptenated LC-depleted epidermal cell population (0.1% LC) induced the same degree of contact sensitivity or tolerance, depending on the route of immunization, as a haptenated 'freshly isolated' epidermal cell population (1% LC). Whereas, a purified population of haptenated LC (85-90%) induced no significant degree of contact sensitivity or tolerance. These results confirm our previous conclusions based the in vivo depletions of Langerhans' cells, and suggest that the epidermal Langerhans' cell is not essential for the induction of contact sensitivity in the guinea-pig. However, this does not exclude the possibility that the LC is involved in the elicitation of contact sensitivity in a sensitized animal.