Immunological tolerance: specificity and experimental induction
THE CONTEXT
Immunological tolerance is antigen-specific unresponsiveness induced by contact with that antigen.
Defining features
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Contact with an antigen abolishes the capacity to mount an immune response against that particular antigen on subsequent administration.
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Immune reactivity to other antigens remains unaffected.
Early antigen exposure and graft acceptance
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An antigen encountered during embryonic life may be recognised as self and fail to induce an immune response.
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A CBA skin graft is ordinarily rejected by a strain A mouse. However, strain A mice injected with CBA cells during fetal or newborn life freely accept CBA skin grafts when they grow up.
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Contact with foreign antigen during embryonic life appears to enlarge the content recognised as self-antigen.
Scope and duration
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Tolerance can develop in adults as well as in embryos and newborns.
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Tolerance may be total or partial and short-lived or long-lasting.