Hyperthermia-induced priming effect in neutrophile granulocytes

Background and Objective: Whole-body infrared-A irradiation (WBIAI) accordi ng to Ardenne is a newly developed version of hyperthermia. In clinical use benefits for patients with chronic infections have been reported. In order to find out more about the immunological background of the method we studi ed the question whether hyperthermia leads to priming effects in human poly morphonuclear leukocytes (PMN). Material and Methods: We therefore investigated the production of reactive oxygen radical species (ROS) measured by lucigenin-dependent chemiluminesce nce after stimulation with N-formylpeptide (FMLP, 10(-6) and 10(-7) M), C5a complement (10(-7) and 10(-8) M) or phorbolester (PMA, 10(-7) and 10(-8) M ) in isolated PMN of 8 volunteers undergoding a 60-min hyperthermia treatme nt with the WBIAI. Blood was drawn 0/60/240/510 min after the start of hype rthermia treatment. In addition, we measured blood pressure, pulse, and tem perature. Results: In 5 cases a significant increase in ROS (p < 0.05) could be measu red beginning 240 min after start of hyperthermia and further increasing un til the 510-min time point. These results suggest a priming effect in PMN l asting far beyond the actual treatment period. The increase of ROS producti on following stimulation with FMLP, C5a or PMA was 60.4 +/- 21.6, 86.0 +/- 23.3, and 63.3 +/- 15.9% (SEM), respectively. Moreover, in all probands the maximal ROS production in PMN was observed 510 min after the beginning of WBIAI treatment. In 3 cases no difference in ROS could be observed. There w as no difference in temperature, blood pressure, and pulse between responde rs and nonresponders. Conclusions: Our results show a hyperthermia-dependent priming effect of RO S production in PMN, suggesting an increase in immune reaction within the o bservation period of 510 min. Further investigations are necessary in order to specify responders and nonresponders and to characterize the results in specific diseases and the constitutions of the patients.