Seasonal Variations of the Immune Response of Ground Squirrels Kept at 22–24 °C

Abstract

Ground squirrels (Citellus richardsoni) were kept at 22–24 °C for 13 months beginning in May 1969. These squirrels did not enter deep hibernation. The primary immune response measured as the serum antibody titer and the number of plaque-forming cells in the spleen decreased to a minimum in Janaury 1970 and recovered during the following spring. It is suggested that the poor immunological response of deep hibernation represents two influences, a primary circennial depression and a secondary exaggeration of this associated with deep hibernation per se.