Immunity

• antibody: a glycoprotein (immunoglobulin) made by specialised lymphocytes in response to the presence of a specific antigen; each type of antibody molecule has a shape that is complementary to its specific antigen
• antigen: a substance that is foreign to the body and stimulates an immune response (e.g. any large molecule such as a protein)
• self Antigen: refers to substances produced by the body that the immune system does not recognise as foreign, so they do not stimulate an immune response
• non-self Antigen: refers to any substance or cell that is recognised by the immune system as being foreign and will stimulate an immune response
• immune response: the complex series of responses of the body to the entry of a foreign antigen; it involves the activity of lymphocytes and phagocytes
• Clonal selection: individual lymphocytes have cell surface receptors that are specific to one antigen; this specificity is determined as lymphocytes mature and before the antigen enters the body
• Clonal expansion: increase in number of specific clones of lymphocytes by mitosis during an immune response