Veterinary Immunology and Serology

FOREIGNNESS

• Antigens are foreign substances.
• The defense cells of the body, normally do not respond to its own molecule (self antigen).
• In general, the antigenicity of a substance is related to the degree of its foreignness.
• Antigen from other individual of the same species is less antigenic than from other species.
• Antigens from related species are less antigenic than those from unrelated (distinct) species.
• Antibodies are not usually produced against the body’s own components.
• In exceptional cases autoantibodies are produced against own tissues (antigen).