Like a thermostat controlling a heater, the hypothalamus uses cortisol to turn off the heat once the production of cortisol matches the stress induced on the immune system. But in a severe infection or in a situation where the immune system is overly sensitized to an antigen (such as in allergic reactions) or there is a massive flood of antigens (as can happen with endotoxic bacteria) the correct set point might never be reached. Also because of downregulation of Th1 immunity by cortisol and other signaling molecules, certain types of infection, (notably Mycobacterium tuberculosis) can trick the body into getting locked in the wrong mode of attack, using an antibody-mediated humoral response when a cellular response is needed. Lymphocytes are the antibody-producing cells of the body, and are thus the main agents of humoral immunity. A larger number of lymphocytes in the lymph nodes, bone marrow, and skin means the body is increasing its humoral immune response. Lymphocytes release antibodies into the bloodstream. These antibodies lower infection through three main pathways: neutralization, opsonization, and complement activation. Antibodies neutralize pathogens by binding to surface adhering proteins, keeping pathogens from binding to host cells. In opsonization, antibodies bind to the pathogen and create a target for phagocytic immune cells to find and latch onto, allowing them to destroy the pathogen more easily. Finally antibodies can also activate complement molecules which can combine in various ways to promote opsonization or even act directly to lyse a bacteria.
GRMF  affects primarily the liver (rather than the kidneys) for some physiological processes.High-potassium media (which stimulates aldosterone secretion in vitro) also stimulate cortisol secretion from the fasciculata zone of canine adrenals — unlike corticosterone, upon which potassium has no effect.Potassium loading also increases ACTH and cortisol in humans. This is probably the reason why potassium deficiency causes cortisol to decline (as mentioned) and causes a decrease in conversion of 11-deoxycortisol to cortisol. This may also have a role in rheumatoid-arthritis pain; cell potassium is always low in RA.Ascorbic acid presence, particularly in high doses has also been shown to mediate response to psychological stress and speed the decrease of the levels of circulating cortisol in the body post-stress. This can be evidenced through a decrease in systolic and diastolic blood pressures and decreased salivary cortisol levels after treatment with ascorbic acid. Factors increasing cortisol levels
Viral infections increase cortisol levels through activation of the HPA axis by cytokines. Intense (high VO2 max) or prolonged aerobic exercise transiently increases cortisol levels to increase gluconeogenesis and maintain blood glucose; however, cortisol declines to normal levels after eating (i.e., restoring a neutral energy balance)
Severe trauma or stressful events can elevate cortisol levels in the blood for prolonged periods. Low-carbohydrate diets cause a short-term increase in resting cortisol (~3 weeks), and increase the cortisol response to aerobic exercise in the short- and long-term. Biochemistry
Biosynthesis
Cortisol is synthesized from cholesterol. Synthesis takes place in the zona fasciculata of the adrenal cortex. (The name cortisol is derived from cortex.)