Immunodeficiencies Flashcards
What are the 2 types of immunodeficiencies
Primary which are congenital and then there are Secondary which are acquired like AIDS
What are the reasons for acquired immunodeficiencies
- Disease like AIDS
- Nutritional
- Medical treatment
What is the first type of primary ID
- Defects in lymphocyte maturation
What is an example where lymphocytes cant mature
An example is SCID, Severe Combined Immunodeficiency.
- This disease is associated with blocks in lymphocyte maturation.
- Half of all clinical cases of SCIDs are X linked where males are severly effected.
- Mutation in gamma chain, required for a range of ILs signaling
- No T cells and NK cells
Why are there no T cells in SCIDs
IL-7 signaling is blocked, IL7 is essential for the survival of T cells in the periphery and for proliferation of T cells at different stages of development in the thymus.
Why are there no NK cells in SCID
NK cells require IL15 for their activation and proliferation. The common gamma chain is part of the receptor so no signaling is achieved
Has to do something with class switching, didnt really understand this concept. The answer is B. IgG is most abundant antibody found in the serra but in this case most of the antibodies would be IgM
What are other genetic reasons for SCID
Autosomal versions of SCID.
- They are caused by ADA and PNP mutations (Adenosine Deaminase and Purine Nucleoside Phosphorylase).
- Mutations in JAK3, same ILs affected as X linked SCID
- Mutations in RAG1 and 2 leading to a complete loss of their function.
If there is some expression of functional RAG1 and 2 then there are some T cells. This condition is called Omen’s Syndrome
What is immunodeficiency generally linked to
Autoimmunity
What is another disease associated with lack of maturation of WBCs
X-linked agammagloblulinemia
- Loss of B cells
- Loss of serum Igs
- Mutations in BTK, X linked
- Autoimmunity
What is another disease associated with lack of WBCs maturations
DeGeorge Syndrome. Part of the chromosome 22 is deleted. This leads to
- Heart defects
- Cleft Palate
- Abnormal development
- Incomplete development of thymus leading to low T cell numbers
What are some of the other defects associated with ID
Defects in lymphocyte development and activation
What is the disease associated with it
X linked Hyper IgM Syndrome
- Mutations in CD40L
- So T cells do not express any CD40L, there is nothing to bind to the CD40 on the B cells, no class switching takes place which leads to B cells inactivation to certain antigens.
- Anytime a B cell gets activated by the other ligands such as MHC 2 or cytokines it makes more IgMs (since there is no class switching) and hence there will be more IgMs
What is another disease she talked about that is associated with B cell inactivation
Autosomal Hyper IgM Syndrome
- Mutations in Activation Induced Deaminase (AID)
- No antibody switching
- No somatic hypermutation
What are some of the other diseases that are more common
Selective Ig’s deficiency, IgA deficiency is more common but there are no adverse symptoms associated with it