Antigen

antigenBinding of any antigen to antibody, the latter one always an immunoglobulin (Ig), occurs through hydrophobic interaction and exclusion of cations from the antigen-antibody interface. On the side of the antigen this surface is termed epitope, whichever its size an impressive structure nevertheless.

On the side of the antibody the surface is a stealth at the N-terminal of the Ig, part of it alongside contributed by heavy (H) chain and part by light (L) chain of Ig. Electrostatic van der Waals forces hold antigen and antibody together, like a handshake with a potential for an on-and-off close encounter.

Recent work published in Clinical & Translational Immunolgy 2017

John Marrack proposed in the 1930ies that antigen-antibody complexes (synonymous: immune complexes) form a lattice structure. In 2017, Joszef Prechl publishes a perspicuous mathematical framework in Clinical & Translational Immunology (doi:10.1038/cti.2017.50): look and try to understand at one of the figures of this paper inserted on the left with permission. In the framework of the Global Alliance for Vaccines and Immunization (GAVI), the vaccine developers test the capacity of their antigens to induce specific antibody formation and efficient immune complex-mediated antigen presentation to follicular dendritic and/or antigen presenting cells – this seems important to me for appraisal of vaccination efficacy.

Nanontechnology, crystallography and proteomics provide evidence, that it is the fine structure of the partners (not only amino acid sequence but also 3D-configuration, carbohydrate substitution, isoelectric points) deciding on ultimate properties of immune complexes conveyed by the complementarity determining regions (CDR) on the Fab recognition site of the Ig molecule.

Influence of some amino acids, like tyrosin, might prevail. Immune complexes are a normal phenomenon serving to remove antigen – however, if they last and remain detectable in peripheral blood or in tissues, they cause disease. Their impact on components of innate immunity is under study.

Last amendment December 2017