Abstract <p>A study of the peculiarities of the formation of adaptive reactions in response to short-term general cooling in practically healthy individuals, depending on the background level of lymphocytes with markers of early activation, was conducted. It has been shown that an increased background level of activated lymphocytes with receptors for IL-2 and transferrin is associated with activation of the hypothalamic-pituitary-adrenal axis, while a lower level is associated with the sympathetic–adrenal–medullary axis. Regardless of the level of lymphocyte activation, the examined patients recorded similar hemodynamic reactions associated with the preservation of thermal homeostasis and activation of thermogenesis mechanisms. A low content of lymphocytes with early activation markers increases the risk of chronic infectious processes in people living in the north due to the higher background level of general inflammation (C-reactive protein, extracellular ATP and LCR), without increasing the phagocytic and secretory activity of neutrophils, as well as an increase in tissue hypoxia after cold exposure.</p>