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Definition - What does Antigenicity mean?

Antigenicity is the term used to define whether and how well the substance attaches to immune cells beginning the immune response process. Antigenicity may also be described as the ability of an antigen or a hapten to bind to a B-cell's or T-cell's receptors.

While sometimes considered synonymous with immunogenicity, antigenicity and immunogenicity are two distinct qualifiers. Every antigen by its nature has some degree of antigenicity. However, if the antigen does not cause what is known as an adaptive immune response, then it does not have immunogenicity.

SureHire explains Antigenicity

Antigens are substances, such as a virus, that the body recognizes as foreign. A hapten is similar to an antigen but must combine with another molecule before it is large enough to be noticed by the immune cells. It is sometimes referred to as an incomplete antigen. Before an immune response can be initiated, these substances must bind to the appropriate receptor.

To trigger an immune response, an antigen binds to the receptor of an immune cell, such as a B-cell or T-cell. The surface of every antigen or a hapten has a unique biological key called an epitope. It is this epitope that binds with a corresponding receptor or antibody.

Antigenicity is the indicator of whether or not, and to what extent a substance can form such a bond. When a person develops allergies or an autoimmune response to something in their own body, it is because that particular substance has become antigenic.

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