Antigeeniantikeha

Antigeeniantikeha, or antigen–antibody complex, denotes the molecular complex formed when a specific antibody binds its corresponding antigen. The interaction occurs between the antigen-binding fragment of the antibody (Fab) and epitopes on the antigen, and is governed by antibody affinity and valency. Complexes can remain soluble or become cross-linked to form lattices that precipitate.

The formation of antigeeniantikeho triggers several immune mechanisms. Binding can neutralize the pathogen or toxin, mark the target for phagocytosis (opsonization), and activate the classical complement pathway through the antibody’s Fc region interacting with C1q. Fc receptors on immune cells also recognize the Fc portion, guiding cellular responses and inflammation. The physical size of the complex influences its fate: soluble complexes are usually cleared by phagocytes, while large lattices can deposit in tissues. The balance between antigen and antibody concentrations (the equivalence zone) determines whether complexes remain soluble or precipitate.

Clinical relevance arises when immune complexes accumulate or deposit abnormally, contributing to type III hypersensitivity reactions such as serum sickness or certain forms of glomerulonephritis and arthritis. Such deposition can trigger inflammation and tissue injury in kidneys, joints, and other organs. In diagnostics, detection and characterization of antigeeniantikeha help assess immune responses, infections, or autoimmune activity. Laboratory methods such as nephelometry, precipitation tests, and C1q-binding assays are used to study these complexes, while ELISAs may measure either antigen or antibody components in a complex.