EPIDERMAL LANGERHANS CELL INDUCTION OF IMMUNITY AGAINST AN ULTRAVIOLET-INDUCED SKIN TUMOR

Langerhans' cells (LC) have been shown experimentally to induce immune responses against many antigens; however, their role in the initiatio n of anti-tumour immunity has received little attention. This study ex amined the ability of murine epidermal LC to induce immunity to an ult raviolet radiation (UV)-induced skin tumour. Freshly prepared epiderma l cells (EC) were cultured for 2 or 20 hr with granulocyte-macrophage colony-stimulating factor (GM-CSF), pulsed with an extract of the UV-1 3-1 tumour, then used to immunize naive syngeneic mice. Delayed type h ypersensitivity (DTH) was elicited 10 days after immunization by injec tion of UV-13-1 tumour cells into the ear pinna, and measured 24 hr la ter. EC cultured with GM-CSF for 2 hr induced antitumour DTH, as did E C cultured for 20 hr without GM-CSF. Conversely, EC cultured for 2 hr without GM-CSF, or EC cultured for 20 hr with GM-CSF were unable to in duce a DTH. Induction of immunity required active presentation of tumo ur antigens by Ia(+) EC and was tumour specific. Thus Ia(+) epidermal cells are capable of inducing anti-tumour immunity to W-induced skin t umours, but only when they contact antigen in particular states of mat uration.