Ground squirrel splenic macrophages bind lipopolysaccharide over a wide range of temperatures at all phases of their annual hibernation cycle.

This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from golden-mantled ground squirrels (Spermophilus lateralis, GMGS), a hibernating mammal, at a variety of in vitro incubation temperatures to determine whether this aspect of immune function is effective at low body temperatures. LPS-binding by ground squirrel macrophages was compared to that of rat splenic macrophages. Macrophages were collected from squirrels at discreet stages in their annual cycle and incubated with fluorescein-labeled LPS (LPS-FITC). The percentage of GMGS that bound LPS-FITC did not change as a function of hibernation season or as a function of incubation temperature. The total amount of LPS-FITC bound per cell was similarly unaffected by season or temperature, however, macrophages from torpid squirrels bound more LPS-FITC than cells from normothermic squirrels. Macrophages of golden-mantled ground squirrels bind LPS at a wide range of temperatures throughout their annual cycle; an ability shared between hibernators and non-hibernators alike.