Microbiology and Immunology 3300B Lecture : Immunology Notes
20 Feb 2012
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Document Summary
Immunological tolerance: tolerance is non-responsiveness to an antigen. Acquired (induced) tolerance is the suppression of a specific, systemic immune response to foreign antigens induced by the specific actions of lymphocytes. Examples of acquired tolerance are fetal tolerance and oral tolerance. Fetal tolerance is the suppression of a specific, systemic immune response to foreign antigens found within a developing fetus. Oral tolerance is the suppression of a specific, systemic immune response against antigens encountered via the enteric (oral) route, like food or gut flora. Types of self-tolerance: central tolerance causes deletion and editing and occurs in the thymus and bone marrow. Antigen segregation forms a physical barrier to self-antigen access to the lymphoid system and occurs in the peripheral organs (thyroid, pancreas). Peripheral anergy causes cellular inactivation by weak signalling without co-stimulus and occurs in secondary lymphoid tissue. Regulatory t cells cause suppression by cytokines and intercellular signals in secondary lymphoid tissue and sites of inflammation.
