Flashcards in Autoimmunity Deck (31)
when does autoimmunity occur?
when the immune systems self-tolerant mechanisms breakdown
what develops in autoimmunity?
autoreactive antibodies and autoreactive T cells develop
what do autoreactive antibodies and autoreactive T cells recognise?
self antigens i.e normal components of the body
Describe the spectrum of autoimmunity.
Can be organ-specific or involve many organs
what causes enlarged thyroid in Hashimotos thyroiditis (organ specific)?
antibodies are directed against thyroglobulin
Describe the changes in Hashimoto's thyroiditis.
-Normal thyroid gland- Acinar epithelial cells (aec)
secrete thyroglobulin into
colloid spaces (cs)
-Hasimotos thyroid gland-Normal architecture virtually
destroyed, replaced by invading cells (ic) - lymphocytes, macrophages
& plasma cells
what do autoantibodies bind to in autoimmunity?
what does antibodies in serum of hashimotos disease patient bind to?
thyroglobulin in colloid
and acinar epithelial cells
what does antibodies in serum of SLE patient bind to?
nuclei (N) of acinar epithelial cells
Name organ-specific autoimmune disease.
-Thyroid i.e hashimotos, thyroiditis
- Adrenal- Addison's disease
-Pancreas-insulin dependent diabetes mellitus
Name non organ-specific disease.
What are important facts of autoimmune diseases?
1. An individual may have more than one autoimmune disease e.g. Rheumatoid Arthritis often associated with SLE
2.Autoimmune diseases can occur in families, Certain HLA haplotypes predispose to autoimmunity
how prevalent is autoimmune disease?
3.5% population have autoimmune disease
what gender is more likely to develop autoimmune disease?
Overall, women are 2.7x more likely than men to develop autoimmune disease
-Female:male ratio can be even higher eg 10:1 in SLE
What can human autoantibodies be directly?
pathogenic i.e graves disease
Describe the cause of graves disease.
-AutoAb produced to receptor for Thyroid Stimulating Hormone (TSH)
-Act on receptor
-stimulate thyroid cell
-overproduction of thyroid hormones
what causes pernicious anaemia?
AutoAb directed against Intrinsic Factor
Describe the cause of pernicious anaemia.
Normally dietary vitamin B12 is absorbed as a complex with intrinsic factor (IF)
In pernicious anaemia autoantibodies directed against IF are produced
Binding of autoantibody to IF prevents interaction with Vit B12
As a result, Vit B12 is not absorbed
Describe immunopathological damage (specific organ).
-When autoAg is localised to a particular organ
-type II hypersensitivity and cell-mediated reactions
-damage due to complement activation and phagocyte degranulation
Describe immunopathological damage (non specific organ).
-immune complexes appear to be pathogenic in systemic autoimmunity e.g. in SLE deposits of IC in the kidney
-type III hypersensitivity reactions
-acute tissues damage
Describe the pathology of rheumatoid arthritis.
-Inflammatory infiltrate found in synovial membrane
-Erosion of synovial cartilage and bone
-IC and neutrophils present in joint space
-IC can arise through self association of rheumatoid
factors = IgG molecules with unusual oligosaccharides
Name 3 examples of autoimmune diseases affecting head and neck (affect thyroid).
-autoimune colloid goiter
Describe the spectrum of autoimmune thyroid disease.
-cell division :stimulation or inhibition
-thyroid hormone synthesis :stimulation or inhibition
What is sjogren syndrome?
Chronic inflammatory autoimmune disorder
how can sjogren syndrome occur?
Can occur in isolation or with SLE, RA or other rheumatic autoimmune disorders
what are the majority of patients with sjogren syndrome?
-Majority of patients are women :
-symptoms develop in 4th-5th decade
-actual onset probably in 1st-2nd decade
How much of the population does sjogren syndrome affect?
1-2% of population
how issjogren syndrome characterised?
-Characterised by a lymphocytic infiltrate in
salivary and lacrimal glands :slow destruction and replacement of glandular tissue with fibrotic tissue
-Lack of salvia and tear secretion : dental caries, oral candida
-condiiton confirmed (60% of patients) by presence in serum of autoantibodies
What are side effects of sjogrens syndrome ?
-dry and lobulated tongue