Susceptibility of human and porcine neutrophils to hypothermia in vitro.

Hypothermia may contribute to serious life-threatening infections. An experimental model has been established in pigs in order to study the effects of hypothermia on host bacterial defenses. The function of blood neutrophils from pigs and humans was examined in vitro at 37 and 29 degrees C. Bacterial killing of Staphylococcus aureus 502A by human neutrophils after 90 and 180 min incubation at 29 degrees C was reduced to 76 +/- 6% and 83 +/- 7% of killing at 37 degrees C. Porcine neutrophil killing was similarly reduced at 90 min (72 +/- 9%) and remained significantly impaired after 180 min (52 +/- 11%). Phagocytosis of ORO-DP-LPS particles by human neutrophils after 5 min at 29 degrees C was 40 +/- 5% of that at 37 degrees C and only 55 +/- 7% after 15 min by which time maximum phagocytosis had occurred at 37 degrees C. Porcine neutrophils ingested significantly less ORO (68 +/- 8%) after 5 min at 29 degrees C and reached normal values by 15 min. Stimulation of hexose monophosphate pathway in human neutrophils for 20 min at 29 degrees C was only 13 +/- 5% of that at 37 degrees C and required 2 h of stimulation to reach normal values. Porcine cells were reduced to 74 +/- 9% after 20 min incubation and reached normal values by 30 min. Directed neutrophil migration as assessed under agarose was impaired for both human (39 +/- 6%) and porcine (20 +/- 4%) neutrophils at 29 degrees C compared to 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)