Ultrastructure and phagocytic activity of rat peritoneal macrophages exposed to low temperatures in vitro

Hypothermia affects various components of the immune system, leading to imp aired immune resistance. To examine the in vitro effect of low temperature on the ultrastructure and phagocytic function of rat peritoneal macrophages , cells were incubated at 4, 10, 24, and 37 degrees C for 60 min. Subsequen tly, their ultrastructure and capacity to engulf latex particles and genera te superoxide anions were evaluated. The results showed a close inverse rel ationship between incubation temperature and ultrastructural changes, i.e., the lower the temperature, the higher the number of altered cells. In addi tion, at lower temperatures the number of cells capable of phagocytosis was reduced; the cells engulfed fewer particles per cell and generated less su peroxide anions. These findings may be relevant for explaining the increase d susceptibility to bacterial infections under hypothermic conditions. (C) 2000 Academic Press.