antigénkötdést

Antigénkötődés, also known as antigen binding, is a fundamental process in immunology. It refers to the specific and reversible interaction between an antigen and an antibody or a T-cell receptor. Antigens are typically foreign molecules, such as proteins or polysaccharides found on the surface of pathogens like bacteria and viruses, or even on abnormal host cells. Antibodies, produced by B lymphocytes, are Y-shaped proteins that recognize and bind to specific antigens. T-cell receptors, on the other hand, are found on T lymphocytes and also recognize antigens, but usually in the context of peptides presented by major histocompatibility complex (MHC) molecules.

The binding site on the antibody or T-cell receptor is called the paratope, and it is complementary in shape and chemical properties to a specific region on the antigen known as the epitope. This interaction is driven by various non-covalent forces, including electrostatic interactions, hydrogen bonds, van der Waals forces, and hydrophobic interactions. The specificity of antigénkötődés is crucial for the immune system's ability to distinguish between self and non-self, thereby mounting an effective defense against invaders while avoiding autoimmune reactions. The strength of this binding is quantified by affinity and avidity, which are critical for the overall efficacy of the immune response.