ABSTRACT
The generation of the immunology system was probably as essential to the evolutionary development of higher organisms as that of the nervous or endocrinological systems. The immunoglobulin molecule is a tetramer, composed of two identical heavy and two identical light chains bound by several disulfide bonds. The immune reaction results from a series of molecular and cellular interactions. The key event in signal transduction is the hydrolysis of membrane-associated inositol phospholipid which generates products acting as second messengers in cell activation. There are three types of human cytotoxic lymphocytes: Cytotoxic T-cell, antigen-specific, major histocompatibility complex (MHC)-restricted, Cytotoxic T-cell of broad specificity, non-MHC restricted, Natural killer cell of broad specificity, non-MHC restricted. Interferons have antiviral, antitumor, and immunoregulatory functions. The immune humoral response with antibody formation to various antigens is an action by which the organism defends itself against potentially injurious factors. Genetically determined immune deficiencies have been known for some time, but knowledge of their nature is far from complete.
