ABSTRACT
This chapter provides an overview of the components and activities of the immune system. The immune response may be divided into innate (sometimes called natural) and adaptive (sometimes called acquired) components. Cells involved in the innate response include various phagocytic cells (neutrophils, monocytes, and macrophages), inflammatory cells (basophils, mast cells, and eosinophils), and natural killer (NK) cells. The innate immune response involves the release of products such as complement (C), acute phase proteins, cytokines, reactive molecules such as those produced during the respiratory burst, and proinflammatory mediators such as leukotrienes and histamine. Other soluble factors are also involved in innate immunity. The adaptive response involves the binding of antigen to surface receptors of antigen-specific B- and T-lymphocytes via an antigen presenting cell (APC) and the subsequent activation and proliferation of the B- or T-cell. It is obvious that cellular interactions are essential for a normally regulated, protective immune response.
