Hyperthermia and immunity. A brief overview.

After many years, hyperthermia (HT) is experiencing a new resurgence as seen by the positive results of many randomized trials all over the world. Tumour immunity similarly is suggested as the fourth modality of therapy for metastatic tumours from renal carcinoma and melanoma. An overwhelming amount of data from animal models and human patients indicate that whole body and locoregional hyperthermia exerts many biological and therapeutic effects on immune competent cells and cytokines. Among these effects, hyperthermia has recently been demonstrated to enhance the antigen presentation and consequently the activity of dendritic cells. This improvement is obtained through several mechanisms: a) increased lymphocyte recruitment and trafficking into the tumour area; b) increased immunogenicity of heat treated tumour cells; and c) increased production of the heat-shock proteins and costimulatory molecules. The effects and mechanisms of HT on immunity, lymphocyte recruitment and dendritic cell stimulation by heat shock proteins are reviewed here. Moreover the use of HT as an innate immunity booster in association with biological response modifiers is suggested.