L22 - Immunological Tolerance Flashcards
low zone tolerance
- tolerance mechanism in which immune system becomes desensitized to an antigen that is present in only small amount
- causes peripheral T-cell selection due to lack of secondary signaling
high zone tolerance
- form of immune tolerance in which the immune system does not react against an antigen present in large quantity
- causes B-cell anergy due to excessive cross-linking
anergy
inactive, quiesent state that self-reacting lymphocytes may enter if they escape negative selection
follicular exclusion
process by which anergic B-cells are excluded from follicles; this would explain why immunodeficient patients also often have autoimmune diseases; they do not have cells that compete in the follicles, allowing the anergic cells to become activated
receptor editing
process by which autoreactive B-cells can undergo further editing
clonal ignorance
observation that the immune system is ignorant to antigens that it does not encounter (i.e., antigens in closed organs)
Treg cells
- induced by Foxp3 or TGF-B
- secrete IL-10 and TGF-B
type I reaction
- caused by IgE
- soluble antigen
- activated by mast cells
type II reaction
- IgG
- cell or matrix associated antigen
- activated by FcR cells (phagocytes and NK cells)
type III reaction
- IgG
- soluble antigen
- activated by FcR cells, complement
type IV reaction
hypersensitivity reaction caused by T-cells
sympathetic opthalmia
disease in which trauma to one eye can lead to an immune attack against the other, uninjured eye
Goodpasture’s disease
type II immune response against collagen IV, resulting in kidney failure
IPEX
- immune dysfunction, polyendocrinopathy, enteropathy, X-linked
- genetic condition characterized by a lack of CD25 T-reg cells
inactive, quiesent state that self-reacting lymphocytes may enter if they escape negative selection
anergy
