Changes

1. Molecular mimicry

1. Molecular mimicry

* Some bacteria and viruses  have antigens that resemble host-cell components and the body then also can initiate an immune response against itself.  

* 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

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 autoantibodys or mediate autoimmunity.

* 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. Inappropriatee MHC expression

3. Inappropriate MHC expression

* Autoreactive T cells are activated because infection stimulates APC and upregulates MHC class II.

* Autoreactive T cells are activated because infection stimulates APC and upregulates MHC class II.