Molecular mimicry

Molecular mimicry occurs when a foreign antigen resembles a body's molecule closely enough that immune responses against the foreign antigen also recognize the body's molecule.

Epitope: The part of an antigen recognized by an antibody or immune-cell receptor. Shared or similar epitopes can let immune receptors bind both foreign and body molecules.
Rheumatic fever: An inflammatory disease that can follow group A streptococcal infection and damage the heart, joints, skin, or nervous system. Antibodies and T cells against streptococcal antigens can cross-react with human tissues.
Michael Heidelberger: An American immunochemist known for quantitative studies of antibodies and antigen–antibody reactions. His work helped establish the chemical specificity underlying proposed antigen cross-reactions.
Autoimmunity: An immune response directed against molecules or cells of the same organism. Molecular mimicry is one proposed route by which an immune response can become self-directed.
T-cell receptor: A receptor on T cells that recognizes peptide fragments presented by major histocompatibility complex molecules. T-cell receptors can cross-recognize pathogen-derived and self-derived peptides.
Guillain–Barré syndrome: A group of acute immune-mediated neuropathies that cause weakness and sometimes paralysis. After Campylobacter jejuni infection, antibodies to bacterial sugars can recognize nerve gangliosides.
Maclyn McCarty: An American physician-scientist who helped establish DNA as the transforming principle in bacteria and studied streptococcal disease. His research helped connect streptococcal infection with immune reactions implicated in rheumatic fever.
Infection-triggered autoimmunity: Autoimmune disease that begins or worsens after an infectious exposure is implicated as a trigger. Mimicry is one mechanism proposed to explain how infection can initiate self-reactivity.
B-cell receptor: A membrane-bound antibody that binds a specific molecular structure and initiates B-cell activation. A B-cell receptor may bind a pathogen structure that resembles a host target.
Campylobacter jejuni: A species of bacteria that commonly causes foodborne gastroenteritis in humans. Its surface sugars can resemble gangliosides targeted in some cases of Guillain–Barré syndrome.

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