Immunology Flashcards
What is autoimmunity defined as?
presence of immune responses against self-tissue/cells
What is the pathogenesis of autoimmune disease?
genetic susceptibilty and then there is an initating event and there is breakdown of self tolerance (loss of immune regulation)
Give an exmple of a monogenic autoimmune disease?
IPEX syndrome
What does IPEX syndrome stand for?
immune dysregulation; polyendocrinopathy; enteropathy and X-linked inheritance
When does IPEX sybdrome present?
presents early in childhood
What are the symptoms of IPEX syndrome?
severe diarrhoea; eczema; very early onset IDDM; autoimmune manifestations
What is the cure for IPEX syndrome?
haematopoeitic stem cell transplantation
What causes IPEX sydnrome?
mutation in FOXP3 gene whic his essential for the delevopment of regulatory T-cells-failure of peripheral tolerance
What is the function of regulatory T cells?
suppress autoreactive T cells
What gives rise to thte hugely diverse popultation of T cells and B cells
random rearragnemnt of Ig heavy and light chain gene segments
What are the tolerance mechanisms required for autoreactive T cells and B cells
central tolerance- removal of self-reactive lymphocytes in primary lymphoid tissues: cells in tissue that present self-antigens, if cell recognises the antigen, the cell dies
peripheral tolerance- inactivation os self-reactive lymphocytes that escape central tolerance- regulatory T cells
What is the difference between MHC and HLA?
HLA is specific to humans whereas MHC is the name across all species
What type of HLA do all nucleated cell express?
class 1: HLA-A; HLA-B;HLA-C
What HLA do specialised APCs also present on their surface?
Class 2 MHC
How many variants of each HLA molecule does each individual possess?
2
What are the HLA types in class 2?
HLA-DP; DLA-DQ; HLA-DR
Why do individual HLA molecules exhibit significant diversity?
to maximise the net ability to bind peptides- on a population level, to maximise ability to respond to antigens and disease
Why do some HLA molecules protect aginast autoimmune diesase whilst some predispose?
some alleles are very able to present self antigen whilst others arent good at it
What suggests that there a hormonal infleucne of lymphocytes function?
there is an lateration in the course of autoimmune diseases during pregnancy
What is molecular mimicry?
an antigen from a particular pathogen shares features with self-antigen
What is an example of molecular mimicry?
acute rheumatic fever after streptococcal infection as strep M5 protein is similar to cardiac tissue proteins
What are the potential mechanisms for autoimmune disease?
molecular mimicry; unrealted bystander activation; super-antigens; antigen sequestration
What is bystander activation?
the stimulation of unrelated (heterologous) T cells by cytokines during an Ag-specific T-cell response
What is antigen sequestration?
when the immune systerm has never seen parts of the body so if during an infection the body sees self-antigens for the first time and it reacts to it
