Antistofftyper

Antistofftyper refers to the different classes of antibodies in mammals, known as immunoglobulins. They are produced by B cells as part of the adaptive immune response; their major determinant is the heavy-chain constant region, which defines their isotype and effector properties.

Isotypes: The five main human isotypes are IgM, IgD, IgG, IgA, and IgE. Some isotypes have subclasses, such as IgG1- IgG4 and IgA1- IgA2, which refine functions. Light chains are either kappa or lambda, present in immunoglobulins.

Structure and function: Antibodies are Y-shaped molecules with two identical heavy chains and two light chains. The variable regions form the antigen-binding sites, while the constant region (Fc) interacts with immune cells and complement. Isotype determines effector mechanisms: IgG and IgA mediate neutralization, opsonization, and migration; IgM is efficient at activating complement and forming pentamers; IgE mediates allergic responses and defense against parasites; IgA protects mucosal surfaces.

Development and class switching: Naive B cells initially produce IgM and IgD. Upon activation, B cells can undergo class switch recombination to produce other isotypes while retaining antigen specificity. Affinity maturation via somatic hypermutation increases binding.

Clinical relevance: Antibody typing is used in serology to determine infection or immunity status. Therapeutic antibodies are engineered as monoclonal antibodies of specific isotypes to exploit particular effector functions. Abnormal antibody production includes autoantibodies and alloantibodies.