Immunology : Course intended for L2 Biology

Abstract

Immunology is the branch of biology that studies the functioning of the immune system in both physiological and pathological contexts. It enables the investigation of the properties of immune effectors and their targets both in vivo and in vitro. The immune system comprises organs, tissues, cells (such as T and B lymphocytes, macro- phages, and leukocytes), and molecules (including antibodies and interleukins) that partici- pate in immunity. Lymphoid organs and tissues are distributed throughout the body. Immune cells circulate within and between these organs via blood and lymph. They communicate either through direct contact (receptor–ligand interactions) or at a distance via secreted molecules (media- tor–receptor interactions). These soluble, secreted molecules are called cytokines substances produced by certain immune cells that act on other immune cells to regulate their activity. This general term encompasses lymphokines, monokines, chemokines, and interleukins.