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Flashcards in Regulation of the Immune Response Deck (13):

What is immunological tolerance?

tolerance is the lack of response to a specific antigen


Immunological tolerance involves

elimination of cell populations reactive to that antigen, neutralization of reactive cell populations, generation of unique cell populations that can produce antigen specific tolerance


mechanisms of tolerance induction

deletion of reactive cells, inactivation of reactive cells (anergy)


Clonal Deletion

immature or developing T cells are deleted. programmed cell death or apoptosis. eliminates autoreactive T cells in the thymus. result of tight association of the autoreactive TCR to MHC presented antigen on specialized thymic dendritic cells


Clonal Anergy

immature cells, exposed to antigen in association with appropriate MHC can be functionally eliminated, especially if these cells do not receive appropriate co-stimulatory signal.


functional deletion

delete antigen specific helper cells and therefore lose CD8+ T cell cytotoxicity or B cell antibody formation that requires help


Generation of suppressor or regulatory T cells

active process involving antigen/MHC specific cells


Blocking of presentation or activation

directed at co-receptors (CD4 or CD8) or at MHC molecules so as to reduce effective presentation


mechanisms of tolerance in T cells

clonal deletion, clonal anergy, functional deletion, generation of suppressor or regulatory T cells, blocking of presentation or activation


mechanisms of tolerance in B cells

clonal deletion of B cells, clonal abortion/clonal anergy/functional deletion


inducing and maintaining tolerance depends on

maturity of host, immunogenicity of a substance, dose of the substance, form of the substance, immunosuppressive drugs



CD4+ T cells that can control autoreactive CD4+ T cells through the release of cytokines. They must be positively selected in the thymus on peptide loaded MHC class II molecules.


Antigen regulation of immune response

amount of antigen, portal of entry of antigen, packaging of antigen, presentation of antigen