Immune regulation within human tumors - contribution of different components of the tumor microenvironment

We have examined the ability of various components of breast, colorectal and ovarian tumours to regulate the activation and function of LAK cells and TILs, immune effectors which have been used as anti-tumour therapies. Tumour cell or supernatants derived from their short-term in vitro culture, inhibited the activation of PBMC by IL-2 but supported the continued proliferation of LAK or TIL cells which had already been activated. Despite being able to enhance or suppress growth of a range of cell lines, a cell-free, soluble preparation (TDS) from primary tumours was uniformly inhibitory to IL-2 activated cells, suggesting that it reflected the immunoregulatory nature of human tumours more accurately than cell-cultures or their supernatants.