Effects of local prostatic hyperthermia on human NK and T cell function.

Studies on lymphocyte subsets, mitogen transformation and NK cytotoxicity of blood mononuclear cells (BMNC) were performed in 30 patients who received transrectal microwave hyperthermia (TRHT) of the prostate. Of the 30 patients, 15 had advanced adenocarcinoma of the prostate (CAP) and 15 had severely symptomatic benign prostatic hyperplasia (BPH). Local TRHT was given twice a week for a total of six sessions. The treatments were administered at 2450 MHz or 434 MHz using a water-cooled rectal applicator. Each TRHT session lasted for 30 min at steady-state temperature controlled on the rectal mucosa at 45 degrees C. Studies of immune reactions were performed before TRHT, at the completion of six TRHT sessions, and at 1, 2, 4, and 6 months from therapy. Identical studies at the same time-interval were performed in 30 healthy male volunteers. In the 15 CAP patients the results of the immune studies obtained before TRHT, including CD4+/CD8+ ratio, PHA and Con-A transformation indices were significantly lower (p less than 0.01) than in the 15 BPH patients and in the 30 normal volunteers. The 15 BPH patients and the 30 normal volunteers all had immune parameters within the normal limits. Following the administration of TRHT in the 15 CAP patients, a transient significant (p less than 0.01) stimulation of the tested cell-mediated immune parameters was observed when compared with the pretreatment values. The peak effect of this stimulation was noted at 2 months with a subsequent decrease. In the 15 BPH patients a lesser degree of immune stimulation was noted. As expected there was no substantial change in the measured cell-mediated immune parameters in the 30 normal volunteers. A significant increase of NK cytotoxic activity was noted following TRHT in CAP patients when compared with the pretreatment results. This activity reached 120-130% of the individual initial values, being significant at p less than 0.01. The finding of transient stimulation of cell-mediated immune reaction, following local hyperthermia in patients with CAP, may be of some clinical relevance and of clinical importance. Additional studies are being formulated to confirm these interesting findings.