The immune system under emotional stress
We found that the number of leukocytes in animals under emotional stress (withdrawn from the experiment after 1 h of emotional stress) was increased by 41.49 % (p < 0.05) compared with the intact group (Table 1 ). Furthermore, the total number of lymphocytes in the animals of group III was increased by 60.07 % (p < 0.01), as did the relative number of lymphocytes (р ˃ 0.05). The absolute number of CD3+ lymphocytes in experimental animals was increased by 1,18 times (p < 0.05), whereas the percentage of lymphocytes remained within the levels of those in the intact group (р ˃ 0.05). Regarding the CD4+ cells, their total number was shown to be increased by 31,57 % (p < 0.05) in group III after 1 h of stress, with their relative number also exhibiting an increasing tendency (р ˃ 0.05). In the case of CD8+ lymphocytes, a similar picture was revealed: increase of their absolute number by 24,07 % (p < 0.05), and relative number by 26,90 % (p < 0.05). We also noted an increas of IRI in group III by 6,42 % (р ˃ 0.05). We also identified an increase of the production capacity of CD3+ lymphocytes, and a 24,42 % decrease of the LMIR migration index in PHA in experimental animals in comparison with the intact group (p < 0.05). Thus, it was suggested that production of cytokines was stimulated on the background of stress.
To determine the state of humoral and non-specific phagocytic links of immunity under stress we evaluated the number of CD19+ lymphocytes in peripheral blood, the concentration of CIC, immunoglobulins in serum, and determined phagocytosis, phagocytic number, as well as performed a NTT-test. Our results showed that 1 h after stress, the absolute and relative number of CD19+ lymphocytes in the blood of animals increased by 1.65 and 1.91 times, respectively, compared with those in the control (p < 0.001). The serum concentration of CIC was observed to be decreased from 1.34 ± 0.04 to 0.71 ± 0.07 g/L (p < 0.001). Against the background of the activation of cellular immunity in the investigated animals, we observed the increase in the levels of IgA and IgG: the concentration of IgA increased by 60 % (p < 0.01), while that of IgG by 88,52 % (p < 0.001), demonstrating the importance of these indicators for assessing the level of humoral immunity under stress.
In animals exposed to emotional stress, the phagocytic activity of blood cells was shown to be increased by 64,32 % (p < 0.01), with the phagocytic number being increased by 82,01 % (p < 0.01). We also found that the NTT-test index was increased by 76.67 % (p < 0.01), indicating the activation of the functional activity of neutrophils.
Thus, we demonstrated here the changes that occurred in humoral immunity of experimental rats undergoing emotional stress, which were primarily characterized by an increase in the number of white blood cells, the absolute and percentile of CD3+ lymphocytes and their subpopulation (CD4+, CD8+), as well as an increase in the functional activity of CD3+ lymphocytes and the protective mechanisms of the body in response to stress. The currently conducted study exhibited the occurrence of activation in all indexes, both in cellular, humoral, and non-specific phagocytic links of immunity, and thus activation of the general adaptive syndrome of an organism at the early period of emotional stress.