Changes

Many animal species have fewer loci than the human e.g. ruminants have no MHC class II DP.

Many animal species have fewer loci than the human e.g. ruminants have no MHC class II DP.

==MHC and Disease==

==MHC and the Disease Process==

* Antigen from a pathogen has to be seen by the host MHC before an efficient immune response can occur

Antigen from a pathogen has to be seen by the host MHC before an efficient immune response can occur so inevitably there is a constant evolutionary battle between the host and potential pathogens. Specifically, there is selective pressure on the pathogen to evolve proteins that do not interact with the host MHC and equally a selective pressure on the host to continue to be able to recognize the pathogen.

** There is therefore a constant evolutionary battle between the host and the pathogen

 

*** There is selective pressure on the pathogen to evolve proteins that do not interact with the host MHC

One consequence of this parallel evolution is that host-pathogen relationships can lead to the selection of particular MHC variants, for example:

*** There is selective pressure on the host to continue to recognize the pathogen

* MHC class II alleles DR13/DR1*1301 are prevalent in Central and Western Africa and impart resistance to malaria.

* The consequence of this parallel evolution is that host-pathogen relationships can lead to the selection of particular MHC variants, for example:

* MHC-DRB1 is prevalent in Western Europe, but rare in the Inuit populations of North America, and is associated with the clearance of hepatitis B infection in Western Europe - but Inuits have the highest incidence of hepatitis B in the world.

** MHC class II alleles DR13/DR1*1301 are prevalent in Central and Western Africa  

 

*** Impart resistance to malaria

In humans there are also strong associations between certain alleles and some autoimmune diseases, for example:

** MHC-DRB1 is prevalent in Western Europe, but rare in the Inuit populations of North America

* Diabetes mellitus

*** Associated with the clearance of hepatitis B infection in Western Europe

* Ankylosing spondylitis

*** Inuits have the highest incidence of hepatitis B in the world

* Rheumatoid arthritis

** In humans there are also strong associations between certain alleles and some autoimmune diseases, for example:

*** Diabetes mellitus

*** Ankylosing spondylitis

*** Rheumatoid arthritis

[[Category:Adaptive Immune System]]

[[Category:Adaptive Immune System]]

[[Category:Lymphocytes]]

[[Category:Lymphocytes]]

[[Category:Image Review]]

[[Category:Image Review]]