Immunogenicity Versus Antigenicity

Introduction

Haptens and the Study of Antigenicity

Antigen-Derived Peptides Are the Key Elements of T-Cell Epitopes

Properties of B-Cell Epitopes Are Determined by the Nature of the Antigen-Binding Site

Epitopes

The Biological System Contributes to Immunogenicity

The Nature of the Immunogen Contributes to Immunogenicity

Substances that can be recognized by the immunoglobulin receptor of B cells, or by the T cell receptor when complexed with MHC, are called antigens. The molecular properties of antigens and the way in which these properties ultimately contribute to immune activation are central to our understanding of the immune system. This lecture describes some of the molecular features of antigens recognized by B or T cells. The lecture also explores the contribution made to immunogenicity by the biological system of the host; ultimately the biological system determines whether a molecule that combines with a B or T cell’s antigen-binding receptor can then induce an immune response. Fundamental differences in the way B and T lymphocytes recognize antigen determine which molecular features of an antigen are recognized by each branch of the immune system.

Immunogenicity and antigenicity are related but distinct immunologic properties that sometimes are confused. Immunogenicity is the ability to induce a humoral and/or cellmediated immune response:

Although a substance that induces a specific immune response is usually called an antigen, it is more appropriately called an immunogen.

Antigenicity is the ability to combine specifically with the final products of the above responses (i.e., antibodies and/or cell-surface receptors). Although all molecules that have the property of immunogenicity also have the property of antigenicity, the reverse is not true. Some small molecules, called haptens, are antigenic but incapable, by themselves, of inducing a specific immune response. In other words, they lack immunogenicity.

Дата добавления: 2014-01-11