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Autoimmune Diseases - Introduction (view source)
Revision as of 14:48, 11 August 2010
, 14:48, 11 August 2010Created page with "==Introduction== '''Autoimmune disease''' is defined as ''a disease state characterised by a specific antibody or cell mediated response against the body's own tissues ('self' a..."
==Introduction==
'''Autoimmune disease''' is defined as ''a disease state characterised by a specific antibody or cell mediated response against the body's own tissues ('self' antigens).
The breakdown of [[Immune Tolerance - WikiBlood|tolerance]] to self antigens and the failure to regulate pathological immune responses are both responsible for autoimmune diseases. It has been shown in mice that thymectomy causes autoimmune disease, and plays a very important role in the recognition of 'self'.
Particular individuals may be more susceptible to autoimmune diseases due to:
===Genetic factors===
Many autoimmune diseases have a familiar component and the Human Leucocyte Antigen (HLA) haplotype is the predominant genetic factor, however having a particular HLA haplotype does not automatically result in the development of an autoimmune disease.
* HLA-DR3/DR4 (MHC Class II):
1. Diabetes Mellitus
2. Rheumatoid Arthritis
* HLA-B27 (MHC Class I):
1. Ankylosing spondylitis
* TNF alpha
* CTLA-4
===Hormonal factors===
Testosterone is protective against Systemic Lupus Erythematosus (SLE) and thus it is not seen in males.
===Environmental factors===
'''''Infection'''''
1. Molecular mimicry
* Some bacteria and viruses have antigens that resemble host-cell components and the body can then also initiate an immune response against itself.
2. Polyclonal activation
* T and B cells activation can occur as a result of an infection resulting in polyclonal activation. This can then cause autoreactive autoantibodies or mediate autoimmunity.
3. Inappropriate MHC expression
* Autoreactive T cells are activated because infection stimulates APC and upregulates MHC class II.
'''''Diet'''''
'''''Stress'''''
{| border="1" cellpadding="2"
!width="150"|
!width="150"|Antibody mediated
!width="50"|Antibody mediated
!width="200"|Cell mediated
|-
| '''Type of hypersensitivity''' || [[Type II Hypersensitivity - WikiBlood|Type II]] || [[Type III Hypersensitivity - WikiBlood|Type III]] || [[Type IV Hypersensitivity - WikiBlood|Type IV]]
|-
| '''Pathogenesis''' || Antibody to cell surface or matrix antigens || Antibody to soluble self antigens || T cell and macrophage activation to self antigens
|-
| '''Examples of diseases''' || [[Immune Mediated Haemolytic Anaemia|Immune mediated haemolytic anaemia (IMHA) || [[Systemic Lupus Erythematosus]] (SLE) || Rheumatoid arthritis
|-
| || [[Immune Mediated Thrombocytopaenia|Immune mediated thrombocytopaenia (IMTP)]]|| || [[Diabetes Mellitus]] type 1
|-
| || [[Myasthenia Gravis|Myasthenia gravis]] || || Hypothyroidism (lymphocytic throiditis)
|-
| || [[Pemphigus Vulgaris]] || || Hypoadrenocorticism (Addisons disease)
|-
| || [[Bullous pemphigoid]] || ||
|}
[[Category:Autoimmune Diseases]]
'''Autoimmune disease''' is defined as ''a disease state characterised by a specific antibody or cell mediated response against the body's own tissues ('self' antigens).
The breakdown of [[Immune Tolerance - WikiBlood|tolerance]] to self antigens and the failure to regulate pathological immune responses are both responsible for autoimmune diseases. It has been shown in mice that thymectomy causes autoimmune disease, and plays a very important role in the recognition of 'self'.
Particular individuals may be more susceptible to autoimmune diseases due to:
===Genetic factors===
Many autoimmune diseases have a familiar component and the Human Leucocyte Antigen (HLA) haplotype is the predominant genetic factor, however having a particular HLA haplotype does not automatically result in the development of an autoimmune disease.
* HLA-DR3/DR4 (MHC Class II):
1. Diabetes Mellitus
2. Rheumatoid Arthritis
* HLA-B27 (MHC Class I):
1. Ankylosing spondylitis
* TNF alpha
* CTLA-4
===Hormonal factors===
Testosterone is protective against Systemic Lupus Erythematosus (SLE) and thus it is not seen in males.
===Environmental factors===
'''''Infection'''''
1. Molecular mimicry
* Some bacteria and viruses have antigens that resemble host-cell components and the body can then also initiate an immune response against itself.
2. Polyclonal activation
* T and B cells activation can occur as a result of an infection resulting in polyclonal activation. This can then cause autoreactive autoantibodies or mediate autoimmunity.
3. Inappropriate MHC expression
* Autoreactive T cells are activated because infection stimulates APC and upregulates MHC class II.
'''''Diet'''''
'''''Stress'''''
{| border="1" cellpadding="2"
!width="150"|
!width="150"|Antibody mediated
!width="50"|Antibody mediated
!width="200"|Cell mediated
|-
| '''Type of hypersensitivity''' || [[Type II Hypersensitivity - WikiBlood|Type II]] || [[Type III Hypersensitivity - WikiBlood|Type III]] || [[Type IV Hypersensitivity - WikiBlood|Type IV]]
|-
| '''Pathogenesis''' || Antibody to cell surface or matrix antigens || Antibody to soluble self antigens || T cell and macrophage activation to self antigens
|-
| '''Examples of diseases''' || [[Immune Mediated Haemolytic Anaemia|Immune mediated haemolytic anaemia (IMHA) || [[Systemic Lupus Erythematosus]] (SLE) || Rheumatoid arthritis
|-
| || [[Immune Mediated Thrombocytopaenia|Immune mediated thrombocytopaenia (IMTP)]]|| || [[Diabetes Mellitus]] type 1
|-
| || [[Myasthenia Gravis|Myasthenia gravis]] || || Hypothyroidism (lymphocytic throiditis)
|-
| || [[Pemphigus Vulgaris]] || || Hypoadrenocorticism (Addisons disease)
|-
| || [[Bullous pemphigoid]] || ||
|}
[[Category:Autoimmune Diseases]]