Effect of temperature on functional activity of macrophages in three different species

Abstract Temperature affects body physiological functions, including immunity in ways that influence survival. This study investigated the effect of temperature on macrophage activation and metabolism across species. Macrophages were isolated from mice, chicken or rainbow trout primary tissue or from macrophage cell lines and were activated with lipopolysaccharide (LPS) or IFN-γ. For mice, both Raw264.7 and primary cells, nitric oxide (NO) production was similar at 35°C and 37°C but dropped dramatically at temperatures below 35°C. At fever temperature (39°C), NO release increased in response to LPS. Young bone marrow derived macrophage (BMDM) and peritoneal resident macrophage (PRM) showed increased protein synthesis at 39°C compared to 37°C. Chicken splenic macrophages (CSM) showed NO responses that were similar at 37, 39, and at 41°C (normal for avian). A fever of 42°C had a large stimulatory effect on NO production compared to 41°C. A chicken liver derived macrophage cell line, HTC, showed the same pattern. They also showed higher protein synthesis at 42°C compared with (41°C) after LPS stimulation. Trout head-kidney macrophages (THM) showed the highest NO responses at 19°C when compared to more typical stream temperatures of 13, 15, and 16°C. They still showed some response at 28 and 37°C. Thus, their macrophages respond at higher temperatures than the fish can tolerate. Stimulated THM cells with LPS at 19°C showed increased protein synthesis compared to 13 and 16°C. We can conclude from our experiments that fish macrophages had a much broader range of temperatures at which they could respond by NO generation and protein synthesis compared to mice and chickens and all had increased responses at fever temperatures.