(ăn′tĭ-jĕn)
[Pronunciation]
[″ + ″]

Any substance capable of eliciting an immune response or of binding with an antibody.
Cellular antigens are proteins or oligosaccharides that mark and identify the cell surface as self or nonself (e.g., as skin, kidney, or nerve cell). Cell surface antigens can stimulate the production of antibodies by B lymphocytes and cytotoxic responses by white blood cells (e.g., granulocytes, monocytes, and lymphocytes).
Antigens on the body's own cells are called autoantigens. Antigens on all other cells are called foreign antigens. Matching certain types of tissue antigens is important for the success of an organ transplant. Inflammation occurs when neutrophils, monocytes, and macrophages encounter an antigen from any source during bodily injury. The antigen may be foreign or an autoantigen that has been damaged and therefore appears to be foreign. Reactions to antigens by T and B cells are part of the specific immune response.
See: autoantigen; cytokine; histocompatibility locus antigen.

Subentries:
allogeneic antigen
alpha-fetoprotein antigen
Australia antigen
carcinoembryonic antigen
CD antigens
CD4 antigen
class I antigen
class II antigen
cross-reacting antigen
D antigen
H antigen
hepatitis antigen
hepatitis B core antigen
hepatitis B e antigen
hepatitis B surface antigen
histocompatibility locus antigen
human leukocyte antigen
H-Y antigen
K antigen
lymphogranuloma venereum antigen
mumps skin test antigen
nuclear antigen
O antigen
oncofetal antigen
p24 antigen
proliferating cell nuclear antigen
prostate-specific antigen
protective antigen
soluble antigen
T-dependent antigen
thymus dependent antigen
thymus independent antigen
T independent antigen
transplantation antigen
tumor-specific antigen