Autoimmunity Flashcards
Define tolerance
mechanisms that protect an individual from potentially silf-reacting lymphocytes
What are the 3 mechanisms of tolerance?
central tolerance: deletes T or B cell clones before the cells are allowed to mature
peripheral tolerance: renders lymphocytes in secondary lymphoid tissues inactive or anergic
life span: elimination of lymphocytes by apoptosis
Define autoimmunity
a generated humoral or cell-mediated response against self antigens
What type of response is not known to cause autoimmunity?
type I, IgE-mediated hypersensitivity responses
What combination of factors determines autoimmunity?
genetic susceptibility, environmental triggers, breakdown of the 3 natural tolerance mechanisms
What are privileged sites?
sites where antigens do not induce either tolerance OR lymphocyte activation. If these antigens are found elsewhere, they become targets of autoimmune attack
What is immunological ignorance?
T cells specific for antigens in privileged sites are in a state of immunological ignorance
What are some examples of privileged sites?
brain, eye, testis, uterus (fetus), hamster cheek pouch
What is the function of AIRE?
AIRE (autoimmune regulator) transcription factor produces proteins that negatively select thymocytes that present self-antigens. Without AIRE, T cells develop and move to the periphery to attack self antigens
What condition does a lack of AIRE gene create?
APECED (autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy), making them suffer from a wide range of autoimmune diseases
What is systemic autoimmune disease?
disease that affects multiple organs and has a tendency to be chronic because autoantigens cannot be cleared from the body
Which cells are affected in Type I diabetes?
specific destruction of the beta-cell producing insulin in the pancreatic islets. Other cells are not destroyed. Peptides from insulin are recognized by the CD8 T cells
Explain multiple sclerosis
T cells attack several brain antigens such as myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein
Explain rheumatoid arthritis
inflammation of the synovium (thin lining of a joint), which damages cartilage and erodes the bone. causes chronic pain and disability
Explain Grave’s disease
Antibody produced by mother passes to fetus and attacks TSH receptor. Causes hyperthyroidism in child. Can be corrected by replacing the plasma of the child
