CP8 - Autoimmune Diseases Flashcards
what are the characteristics of autoimmunity?
- theoretical concept
- inherited
- genetically determined
what are the characteristics of autoimmune disease?
- distinct clinical entity
- due to a breakdown of self-tolerance
- caused by environmental factors acting on a favourable genetic background
what are the 3 contributing factors of autoimmune disease?
- genes
- immune regulation
- environment
what is central tolerance?
carried out in the bone marrow for b cella and thymus for t cells. it involves conditioning the b and t cells not to attack self antigens
what is positive selection?
cells are let free if they don’t attack self antigens
what is negative selection?
cells are destroyed if they attack self antigens
what is peripheral tolerance?
if some t cells enter the circulation and attack self antigens, lymph nodes will destroy them (similar system for b cells)
which genes are thought to have a role in shaping the behaviour of T cells?
class II MHC
what is the effect of a mutation in FoxP3?
failure in development of Treg cells, severe autoimmunity from birth
what is the effect of mutation in PTPN22?
easier activation of T cells, leading to a much stronger response than expected.
what are the risk factors for autoimmunity?
- genetics
- sex (due to hormonal influence, women more prone)
- age - elderly more prone
- concealed antigens in the body may be recognised as foreign by the immune system, e.g., nucleus, eye, testis
- environmental triggers
- changing the amount or nature of self antigens
which environmental triggers could act as risk factors for autoimmunity?
- infection - activates immune system but could cause autoimmunity if it goes too far
- trauma
- smoking
what is citrullation?
conversion of the amino acid arginine in a protein to the amino acid citrulline. one of the causes of RA
what is the disease mechanism which causes SLE?
failure to clear apoptotic debris, increasing the availability of sequestered antigens inside the cells
how do t cells cause inflammation?
- releasing inflammatory cytokines
2. helping b cells make antibodies