a 2 -Macroglobulin A serum protease inhibitor with a broad range of specificities which blocks members of all four known classes of endopeptidases. It contains a unique thiol ester group which, when cleaved by the proteases, results in a covalent bond between protease and inhibitor. Concordantly, the protease becomes entrapped by a conformational change of the inhibitor. a 2 -Macroglobulin has been implicated to play a role in lipopolysaccharide sensitivity, neutralization of transforming growth factor-b and in Alzheimer's disease. It binds to the cell surface receptor CD91.
Adaptive immunity
Immunity to infectious or other antigens that improves in quality and intensity from the first to the second encounter with the antigen, in contrast to innate immunity which involves always the same immune reactions of the same intensity with every antigen challenge. Adaptive immunity is based on the selection and expansion of antigen-specific T and B lymphocyte clones. The B lymphocytes switch thereby from IgM to IgG production which have a higher affinity for the antigen.
Adhesion molecule
Cell surface receptor for cellΒ±cell and cellΒ±matrix adhesiveness. They are implicated in stable cellΒ±cell contacts in tissues as well as in the transient attachments of migrating cells, and play a role in transmigration of leukocytes through the endothelial cell layer of blood vessels and in the interaction of T lymphocytes with their stimulator or target cells. Several families of adhesion receptors with different functions have been described including cadherins, selectins, addressins, integrins, Annexins and members of the immunoglobulin superfamily, such as the intercellular adhesion molecules (ICAMs). Some adhesion molecules, e. g. some integrins, also transmit signals into the cell and/or out of the cell.
Adjuvant
Material co-administered with specific antigens to improve the vaccination effects. Adjuvants are often derived from microorganisms but may also be cells like dendritic cells, subcellular components such as heat shock proteins, cytokines, chemokines, lipids of various origin, oligonucleotides or inorganic compounds such as aluminum hy-Cancer Immune Therapie: