The influence of temperature and season on mitogen-induced proliferation of ground squirrel lymphocytes

Lymphocyte proliferation is a prerequisite for most aspects of the mammalian acquired immune response. Splenic lymphocytes from golden-mantled ground squirrels collected at different phases of hibernation were stimulated in vitro with several mitogens to measure proliferative ability at several temperatures. No differences were seen in lymphocyte proliferation at any of the temperatures tested between animals at different stages of hibernation. No proliferation was detected at 5 degreesC. T cell mitogens induced significantly higher proliferation at 37 degreesC than at 27 degreesC in lymphocytes from both summer and hibenrating animals. AB cell mitogen induced similar proliferation at both 27 degrees and 37 degreesC in cells from summer and hibernating animals. Lymphocyte proliferation appears to be highly temperature-dependent in both summer and hibernating animals. Therefore, interbout arousals are essential for the production of a successful acquired immune response during hibernation.