Specific Release of Cytokines by Lymphocytes Infiltrating Human Melanomas in Response to Shared Melanoma Antigens

Abstract

Lysis of autologous and human leucocyte antigen (HLA)-matched allogeneic melanomas by cultured human tumor-infiltrating leukocytes (TIL) suggests that shared melanoma antigens (Ag) exist and are recognized by TIL in the context of self major histocompatibility complex (MHC) molecules. We have recently shown that cytokine release by TIL is another indicator of the specific interaction with autologous tumor. To determine if recognition of shared melanoma Ag can also induce cytokine release, seven melanoma TIL, which lysed autologous tumor, were co-cultured with autologous tumor or with 7-12 HLA-matched or unmatched melanoma stimulators for 6-24 h. Supernatants were collected and assayed by ELISA for the presence of granulocyte/macrophage colony stimulating factor (GM-CSF), interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, and IL-6. Among five of six melanoma TIL for which autologous tumor was available, autologous melanoma cells stimulated specific release of at least one of three cytokines: GM-CSF, IFN-gamma, and TNF-alpha. Neither IL-4 nor IL-6 secretion by three TIL cultures tested was enhanced upon contact with tumor. For six of seven TIL cultures, HLA-matched allogeneic melanomas also stimulated significant cytokine release; HLA-A1, -A2, -A24, -B8, and -Cw7 were identified as possible restriction elements. The cytokine secretion induced by both autologous and allogeneic HLA-matched melanomas could be blocked by an anti-MHC I antibody. These data suggest that cytokines can be specifically released by TIL recognizing a shared melanoma antigen in the context of self MHC molecules.