[NK cells, chemokines and chemokine receptors]

NK cells are an important component of natural immunity, which provides a defence response against viruses, bacterial and parasitic intracellular pathogens and tumour cells. NK cells are capable of rapid responses without prior sensitization and cytotoxic response is independent of the presence of the antigens of the major histocompatibility system. NK cells produce a number of cytokines (e.g. INF-gamma, GM-CSF and TNF-beta) and chemokines and in this way they regulate both the natural and acquired immune response. By contrast, NK cells are regulated both positively and negatively by cytokines and chemokines produced by other immune cells. Attention is focused on the possibility of influencing the tumour process by using cytokine- and chemokine-activated NK cells. In studies in mice models as well as in several clinical trials, it has been shown that the presence of cytotoxic cells in tumour stroma is associated with a more favourable prognosis of cancer.There is also plenty of evidence that in tumour stroma a number of cytokines and chemokines are produced which may have ambivalent effects.