In vitro lymphocyte response to autologous melanoma: Clues in designing new adoptive immunotherapy protocols

Recent studies indicate that different types of antitumour lymphocytes (T and non-T) can be generated in vitro and in vivo after exposure to recombinant interleukin-2 (rIL-2). In vitro it is possible to selectively expand the CD3 cells by using anti-CD3 monoclonal antibody and rIL-2. Adherence can select a minor subpopulation of lymphokine-activated killer (LAK) cells (A-LAK) endowed with a higher lytic activity. We have investigated whether melanoma-specific T-lymphocytes can be obtained to be used for therapy or endogenously expanded in vivo by the appropriate use of limited amounts of rIL-2. Clonal analysis of lymphocytes obtained either from tumour lesions or from blood indicated the existence of melanoma-restricted T-lymphocytes, both with cytotoxic or helper function. Though a minority, these cells can be generated and expanded with low amounts of rIL-2 (3-30 Cetus U/ml) in the presence of autologous melanoma and B-cells. The use of rIL-1 and rIL-4, together with rIL-2 at certain phases of T-lymphocyte growth, can help in expanding more selectively the melanoma-specific cells. These T-cells are major histocompatibility complex-restricted in their killing but they also need to see adhesion molecules (ICAM-I) on the target cells. New clinical protocols can thus be conceived on the basis of some of these results.