The immune system is a system for self-recognition and maintaining homeostasis. It is an extremely complex network that extends throughout the body, and is able to recognize and defend the organism against a theoretical infinity of challenges. The defence against pathogens is mediated by early stages of innate immunity and late adaptive immune responses. Macrophages and neutrophils, along with NK cells, complement and defensins participate in the innate immune mechanism, which all together constitute the first line of defence. They all need a basic capacity to distinguish between self and foreign, and danger or non-danger signals with the involvement of toll-like receptors (TLR). By picking up, processing, and presenting antigens, macrophages constitute the link between non-specific and specific branch of the immune system which mainly consists on the different subpopulations of lymphocytes and their products. This specific branch constitutes the adaptive response, which needs the previous contact with antigens and it is developed through a clonal proliferation of lymphocytes (T, cytotoxic lymphocytes, and B lymphocytes) resulting in the release of specific antibodies.
When the immune system does not work properly, the consequences could be serious. Immune system disorders include:
When the immune system does not work properly, the consequences could be serious. Immune system disorders include:
- Allergy and asthma: inappropriate immune responses to usually harmless substances
- Immune deficiency diseases: disorders with decreased resistance to infections
- Autoimmune diseases: diseases where the immune system attacks by mistake their own cells and tissues
Crosstalk:
Immune system
The side effects of EPO on the immune system are still not clear. Some investigations suggest that artificial oxygen carriers can impair the immune system. However, investigations in animals have shown that premature rats with lower levels of red blood cells, displayed a decrease in immune function, such as T cell responsiveness and TNF-α production (compared with mature rats).
Corticotropin has been used to increase blood levels of endogenous corticosteroid. Administration of corticotropin is considered to be similar to the systemic administration of corticosteroids which is well known to suppress immune response at pharmacological concentrations. They decrease lymphocyte mediated adaptive response which could increase susceptibility to infection.
Growth hormone (GH) has been described in general as an immunopermissive hormone. Exogenously administrated GH is protective in many models of infection in which macrophages play important effector roles. There are studies on the physiological role of GH in the immune response and the variations of this hormone following exercise, but there are no studies which link the administration of this hormone as a doping substance and thereby its effects on the immune system.
GH mediates the acute effects of exercise on neutrophils. Intravenous GH injection induces a marked neutrophil. An increased respiratory burst immediately after maximal exercise performed by cross-country skiers was found in parallel with increased serum GH levels. However, although changes in the concentration of GH may also contribute to changes in the respiratory burst of neutrophils (related to their microbicide capacity) over repeated exercise bouts or in response to training, the results are confusing. There are no studies which link the administration of this hormone as a doping substance and its effects on the immune system.
Corticotropin has been used to increase blood levels of endogenous corticosteroid. Administration of corticotropin is considered to be similar to the systemic administration of corticosteroids which is well known to suppress immune response at pharmacological concentrations. They decrease lymphocyte mediated adaptive response which could increase susceptibility to infection.
Growth hormone (GH) has been described in general as an immunopermissive hormone. Exogenously administrated GH is protective in many models of infection in which macrophages play important effector roles. There are studies on the physiological role of GH in the immune response and the variations of this hormone following exercise, but there are no studies which link the administration of this hormone as a doping substance and thereby its effects on the immune system.
GH mediates the acute effects of exercise on neutrophils. Intravenous GH injection induces a marked neutrophil. An increased respiratory burst immediately after maximal exercise performed by cross-country skiers was found in parallel with increased serum GH levels. However, although changes in the concentration of GH may also contribute to changes in the respiratory burst of neutrophils (related to their microbicide capacity) over repeated exercise bouts or in response to training, the results are confusing. There are no studies which link the administration of this hormone as a doping substance and its effects on the immune system.
