Agonistic Antibody & Antagonistic Antibody

Agonistic Antibody

It is an antibody that stimulates or activates an organ. For example, agonistic antibodies can fight against the thyrotropin receptor in Grave disease in order to stimulate the thyroid gland to release thyroid hormones which can be used to produce hyperthyroidism.

Antagonistic antibody

It is a kind of drug, enzyme, inhibitor, or hormone that weakens or blocks another molecule or signal transduction pathway. Antagonism is simply the meaning of resistance. Antagonists are not a single drug name. There should be other prefixes in front of it. For example, there is a kind of "calcium antagonist" in high blood pressure drugs. His role is to resist excessive calcium into the cells, thereby reducing blood pressure. An antagonist, like an agonist, binds to a receptor but does not induce a conformational change that produces a change in biological activity. An agonist is capable of inducing a conformational change in the receptor and causing biological activity. Antagonist refers to a drug that has only a strong affinity with the receptor, but has no intrinsic activity, so it does not produce an effect, but can block the binding of the agonist to the receptor, thereby counteracting or eliminating the action of the agonist.

Differences between agonistic antibody and antagonistic antibody

Both types of antibodies are able to bind to receptor, but at different sites, because the two antibodies are different clones with different hypervariable regions. Although they may have the same isotype IgG or a subtype, HVR determines where the antibody binds to the receptor. This may occur at the ligand binding site of the receptor or more or less somewhere in it.

One of the reasons why one will activate the receptor and the other will stop it is as follows:

Binding of Ab1 to the receptor can occur at a site that mimics a ligand binding event that causes a conformational change in the receptor and allows it to signal into the cell.

Ab 2 can bind to the receptor even near its ligand binding site, but binds in a manner that does not cause a conformational change, so that no signal transduction occurs. Due to this binding of Ab 2, any subsequent binding of the "true" ligand is blocked, mainly due to steric hindrance, simply because the giant IgG molecule blocks the pathway to the ligand binding site and The target has a high affinity epitope. In theory, you can have identical antibody clones, but not like IgG molecules, but like IgA or IgM, although their half-life in the system is likely to change, they still do the same.

Among these, agonistic antibody works well in the therapy of cancer, for monoclonal antibody could act as agonists of receptors, essentially it can replace the activity of the normal ligand. When an antibody binds to a receptor in a manner that mimics physiological ligand binding, agonist activity can occur, resulting in antibody-mediated agonism. So far, agonistic antibodies in pre-clinical and clinical research in the most can target the TNF family member, such as OX40, CD27,4-1BB and DR5.

Those are differences between two types of antibodies.

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