[Function and prognostic significance of immune cells infiltrating human tumors]

The presence of a mononuclear infiltrate has prognostic importance in a variety of human cancers. The infiltration by different cell types, mainly T lymphocytes and dendritic cells has been correlated to tumor size, stage, metastatization, and patients' survival. Their pathophysiological role is influenced by the cell types, their localization (intra- or peritumoral), and by tumor characteristics or patient subgroups. The prognostic significance of the different cell populations in the individual tumor types is frequently controversial, which is due, in part, to their multiple functions; for example, tumor-associated macrophages are involved in the regulation of angiogenesis beside their immunologic functions. Moreover, the presence of immune cells in the tumor does not guarantee the development of an efficient immune reaction, consequently, the degree of infiltration does not necessarily correlate with the intensity of the immune response. Therefore, recent studies emphasize the importance of the assessment of the functional and activation state of tumor infiltrating lymphocytes. Here we summarize results on the prognostic role of infiltrating mononuclear cells in human neoplasms, and present our data on studies performed on cutaneous malignant melanoma.