In vitro effect of temperature on phagocytic and cytotoxic activities of splenic phagocytes of the wall lizard, Hemidactylus flaviviridis

The in vitro effect of temperature on phagocytosis, nitric oxide production and interleukin-1 (IL-1) secretion by splenic phagocytes isolated from the wall lizard (Hemidactylus flaviviridis) demonstrated that changes in tempe rature altered non-specific defenses. The LPS-induced percentage phagocytos is and phagocytic index were recorded maximum at 25 degreesC. The phagocyti c activity declined considerably when the phagocytes were incubated at low (7 and 15 degreesC) or high (37 degreesC) temperatures. The presence of bac terial lipopolysaccharide (LPS) in the incubation medium could considerably enhance the phagocytic activity of splenic phagocytes. A similar temperatu re-related effect was also observed on LPS-induced cytotoxic activity of ph agocytes. LPS could stimulate the nitrite release indicating nitric oxide p roduction only at 25 degreesC. Likewise, the proliferative responses of imm ature rat's thymocytes to LPS-induced phagocyte-conditioned medium suggest that IL-1 secretion was enhanced when phagocytes were cultured at 25 degree sC. This suggests that 25 degreesC is the optimal temperature for phagocyte functions in H. flaviviridis. The decrease or increase in temperature othe r than at 25 degreesC dramatically suppressed the phagocyte activities. (C) 2001 Elsevier Science Inc. All rights reserved.