self

self (slf)

n. pl. selves (slz)

1. The total, essential, or particular being of a person; the individual.

2. One's consciousness of one's own being or identity; the ego.

3. That which the immune system identifies as belonging to the body.

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self

a term used to denote an animal's own antigenic constituents, in contrast to 'not-self', denoting foreign antigenic constituents. The 'self' constituents do not normally elicit an immune response, i.e. there is self-tolerance, whereas the antigens which are 'not-self' do elicit an immune response. Self reactive lymphocytes, particularly T lymphocytes within the thymus, are eliminated. The breakdown of self-tolerance by a number of mechanisms is the basis for autoimmune diseases. See also immunity.