Production of tumor necrosis factor in cells of hibernating ground squirrels Citellus Undulatus during annual cycle

TNF production has been studied in peritoneal macrophages and splenic T cel ls of Arctic Yakutian ground squirrel (Citellus Undulatus Pallas) in hibern ating and awake animals in winter and in prehibernating autumn as well as i n active euthermic spring-summer animals. A high level of TNF production in macrophages of ground squirrel is observed over the active period and duri ng arousals in winter. There are no significant season variations in TNF pr oduction in splenic T lymphocytes of ground squirrels. This suggests the ma jor role of activated macrophages in the arousals of hibernating animals. T lymphocyte proliferation in ground squirrels in the active period is highe r than in winter, and the most significant seasonal variations are found in T cell mitogenic response, which increases in spring-summer period. Eviden ce is presented that functional activity of macrophages of squirrel in autu mn has much in common with that in winter rather than in spring-summer peri od. (C) 2000 Elsevier Science Inc. All rights reserved.