Autoimmunity Flashcards
What is autoimmunity
Failure of organism to recognise its own constituent part as non-self
What are factors involved in developing autoimmune disease
Genetics - HLA
Hormonal - W>M
Environment
Immune regulation
Examples of environment
UV sun = apoptosis in SLE exposing T cell to ANA Ab which as seen as foreign
Infection = breakdown in tolerance
Chemicals / drugs
What are the pathogenetic mechanisms of different autoimmune disease
Cell mediated
Ab mediated
Immune complex mediated
Mixed / atypical
What happens in Cell mediated
Breakdown in immune tolerance
T cell bypass
T / B cell discordance
What is T cell bypass
B cells usually activated by alerted T cells
Can be bypassed by polyclonal activation of B cells e.g. super antigens in infection
What is T / B cell discordance
T and B cells should respond to same antigen
If they don’t B cells use ANY T cell stimulated by antigen to do the work
What diseases are cell-mediated autoimmune
DM
Chron’s
Psoriasis
Coeliac
What happens in DM
Autoreactive T cells against pancreatic islet cell antigen = destruction
What happens in Chron’s
Foreign pathogen in gut = APC to CD4
Autoreactive T cells attack
Inflammation
What gene associated
NOD2
What happens in Psoriasis
Autoreactive T cells attack skin associated antigens leading to inflammation and thickening
What happens in coeliac
B cells for transglutmainase (anti-TTG Ab) helped by T cells to recognise gliadin (concordance)
APC picks up gladden and presents to T cell
Recognise as foreign and attacks
If can’t find gliaden attacks other cells in gut
What happens in Ab mediated
Ab binds to self antigen due to failure of B cell
Leads to damage by Fc receptor MO +- complement
What is it an example of
Type 2 hypersensitivity reaction