Published online by Cambridge University Press: 05 June 2015
Cytokines were introduced in Chapter 1 (section 1.4.9) as signaling molecules secreted by cells of the immune system. They are important components of the interconnected neural, endocrine and immune systems (see Figure 1.2). For example, various types of stress, including academic examinations, influence the immune system via an activation of the hypothalamic-pituitary-adrenal axis and the secretion of glucocorticoids (see Figures 6.1 and 6.4). Likewise, an immune response that stimulates white blood cells to produce cytokines, for example following an infection, has effects on the hypothalamic control of various hormones such as ACTH, GH and PRL. Since most immune cells have receptors for these hormones, the immune system is affected directly by pituitary hormones as well as by adrenal output of glucocorticoids or catecholamines (Figure 1.2). The immune system, therefore, via secretion of cytokines, participates in a classic neuroendocrine feedback system. There are also profound sex differences in immune responses and some of this variation is due to the effects of sex steroids, such as testosterone and estradiol. For example, 80 percent of patients with autoimmune diseases (e.g. rheumatoid arthritis; multiple sclerosis) are women; 60 percent of adult asthma cases are women; and men are at least 1.6-fold more likely than women to die from malignant cancers (Klein 2012).
This chapter begins with an overview of those cells of the immune system that secrete cytokines, and then discusses the immune functions of the thymus gland and its hormones. The roles of cytokines in the immune response to antigens (i.e. substances that cause an immune response) and in the development of blood cells are then summarized and the neuromodulatory effects of cytokines on the brain and neuroendocrine system are examined. This is followed by a discussion of the neural and endocrine regulation of the immune system and the hypothalamic integration of neural, endocrine and immune systems.
The cells of the immune system
The immune system consists of many different cell types, including several that secrete cytokines; i.e. monocytes, macrophages, T lymphocytes (T cells), B lymphocytes (B cells) and natural killer (NK) cells (see Figure 13.1).
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.