B-lymphocytes, providing humoral immunity, are produced from hematopoietic stem cells in the bone marrow. Mature B lymphocytes are displaced in the blood and lymphatic vessels between the lymph nodes and the spleen. When stimulated with an appropriate antigen, B-lymphocytes multiply rapidly, forming a group of identical cells (clone) that produce specific antibodies, also called immunoglobulins – they are designed to neutralize the corresponding antigen.
T-lymphocytes act on antigens directly, providing cellular immunity. They are also produced from the hematopoietic stem cells of the bone marrow, which mature and differentiate in the thymus and then migrate to the periphery. Specialized T-lymphocytes are involved in the regulation of B-lymphocytes. Other leukocytes, called macrophages, act non-specifically, enhancing the ability of antigens to stimulate lymphocytes. In addition, a system of blood proteins, called complement, together with antibodies, is involved in the destruction of antigens. It is also assumed that they control the appearance of cancer cells and eliminate them.
The interaction between immune cells is carried out with the help of mediators of the immune system, called cytokines, the most important of which are interleukins. To assess the functional state of the immune system, the study of the proliferative response of T and B lymphocytes to mitogens, substances that stimulate the proliferation of T and B cells, is important. Experimental evidence suggests that the nervous, endocrine, and immune systems regulate each other’s activities and jointly participate in maintaining homeostasis.
The functional state of the central nervous system has a significant effect on the immune system. The cells of the immune system have receptors for most neurotransmitters, neuropeptides, and steroid hormones. On the other hand, the immune system can affect the nervous system. Thus, cytokines – interleukin-1 (IL-1) and interleukin-6 – increase the slow-wave phase of sleep, reduce the level of glucose in the blood, cause depression and fatigue. In the nervous system, receptors for mediators of the immune system, cytokines, are associated with the system of secondary messengers.
The brain and the immune system interact with each other through two main channels: 1) with the help of the autonomic nervous system and 2) the neuroendocrine system. Vegetative noradrenergic and cholinergic fibers innervate the bone marrow, thymus, spleen, and lymph nodes. It is shown that in low concentrations the mediator of the sympathetic autonomic nervous system norepinephrine stimulates, and in large concentrations – suppresses many immune functions. (V.V. Abramov, 1991)