Tolerance, Autoimmunity and AI disorders Flashcards
(52 cards)
true or false: self-recognition/tolerance is a critical process
true (duh)
Failure to recognize self antigens results in what type of disease?
autoimmune diseases
Immune responses require what two mechanisms to happen?
APC presentation of foreign Ag and signal from MHC molecule on host’s cells
Define Tolerance
Lack of immune response to self antigens
A major mechanism of self-tolerance (autoreactivty) is the elimination of what cells?
Elimination of self-reactive immature lymphocytes
Failures of tolerance can result in what abnormalities?
- autoimmune reaction to self-Ag
- hypersensitivity
- autoinflammatory disorders
B cells undergo two selection processes during maturation. Briefly describe the main focuses of these stages.
Positive selection: signals for survival
Negative selection: T cells in thymus that lack self-MHC are eliminated (must go through this selection before achieving immunocompetence)
Peripheral tolerance: process of negative selection in periph lymph tissues and prim lymph tissues
True or false: T cells dont show a marked difference in tolerance at different stages of maturation
true
What are the three pathways recognized for T cell tolerance?
Clonal abortion
functional deletion
t cell suppression
What organ is responsible for deleting autoreactive t cells that have potential to cause autoimmune diseases?
Thymus
What are the four pathways of B cell tolerance?
clonal abortion
clonal exhaustion
functional deletion
Ab-forming cell blockade
True or false: potential for autoimmunity is constantly present in immunocompetent individuals
true
What are some focuses of genetic factors in autoimmunity?
- Focuses on common allelic variants (not mutations)
- familial aggregates common
- tendency for more than one autoimmune disease to occur in same individual
- more frequent in women
What are some factors that influence the development of autoimmunity?
Pt age (incidence increases with age (peak at 60-70yrs))
Exogenous factors (UV, drugs, virus, chronic infectious disease)
What are the three major phases of Autoimmune disease?
Initiation (genetic predisposition/environ triggers)
Propagation (cytokines,epitope spreading)
Resolution (cell intrinsic/extrinsic)
What is included in Antibodies to Antinuclear AB? (ANAs)
DNA, histones and nonhistone protein ab
What is the hallmark of autoimmune diseases?
tissue injury caused by T lymph or ab reactivity to self
What is the role of the innate system in tissue injury?
neuts and macros are recruited to sites of ischemic injury
Macrophages release proinflam mediators and initiate programs to help in clearance of dead tissue/repair (may be detrimental if chronic)
What cells contribute substantially to multiple autoimmune disorders?
B cells
What are some characteristic of Organ-specific autoimmune diseases?
- Produced by T cells or Ab restricted to one organ
- lesions produced by tissue damage and autoantibodies limited to one organ
- Examples: Type I diabetes, MS, thyroid
What are characteristics of Organ-nonspecific autoimmunity?
- systemic autoimm disease caused by - circulation of Ab or imm complexes and affects multiple organs
- lesions and autoab not confined to one organ
- Examples: SLE, RA
What is the characterization of midspectrum disorders?
localized lesions in a single organ and by organ-nonspecific autoantibodies
Cardiovascular disorders: what are some key factors about vasculitis?
- primary immune disorder of blood vessels
- circulation of immune complexes
- inflam lesions of blood vessels produce injury or necrosis of blood vessel wall
- Ab to endothelial cells may also contribute to vasculopathy
Cardiovascular disorders: what are some key factors about carditis?
- Primary imm disorder of the heart
- reaction of cardio myocytes to imm injury
caused by a variety of conditions (Rheumatic fever, lyme, cardiac transplant rejection)
