Final Immunodeficiencies Flashcards
What are the two types of immunodeficiencies?
-primary and secondary
What is primary immunodeficiency?
-inherited conditions resulting in a defect in leukocyte development or function
What consequences for the patient does primary immunodeficiency cause?
- renders the patient susceptible to cancer and infection
- this susceptibility varies greatly depending on the defect
How many general classes of primary immunodeficiencies are recognized?
8 general classes consisting of over 120 specific conditions
List all the deficiencies that are included under primary
- combined B and T-cell
- mostly B cell
- mostly T cell
- myeloid
- complement
How are primary immunodeficiencies classified?
According to the developmental stage of the cells involved
What are the consequences of primary combined B and T cell immunodeficiency? (6)
- SCID
- severe and recurring infections early in life
- frequent viral or fungal infections
- lymphophenia
- fatal if untreated
- bone marrow transplant
What is lymphophenia
Low circulating lymphocytes
What is ADA deficiency?
Mutation in adenosine deaminase
What does ADA deficiency cause?
-causes combined B and T-cell immunodeficiency
How does ADA deficiency cause immunodeficiency? (4)
- ADA normally breaks down adenosine
- if deficient there will be a build up of adenosine and S-adenylhomocyteseine
- this inhibits ribonucleotide reductase
- inhibiting DNA replication and high levels of S are cytotoxic
What is autosomal SCID caused by?
- mutation in DNA repair or RAG 1 or 2
- failure to successfully rearrange V(D)J genes
What does autosomal SCID cause?
-causes combined B and T-cell immunodeficiency
What causes X-linked SCID?
Mutation in IL-R common gamma chain
What does X-linked SCID cause?
-combined B and T-cell immunodeficiency
What does the mutation caused by X-linked SCID result in
A defect in cytokine signalling
What causes X-linked Hyper-IgM Syndrome?
Mutation in CD40L
What does X-linked Hyper-IgM Syndrome cause?
B cell immunodeficiency
How does X-linked Hyper-IgM Syndrome cause immunodeficiency? (3)
- low levels of blood IgG, IgA and IgE and elevated IgM
- lack of CD40L leads to a lack of costimulation of B cells which leads to reduced B cell activation in response to T-dependent antigens
- failure to produce germinal centres, no class-switching, reduced hypermutation and few memory cells
What does Autosomal Hyper-IgM Syndrome cause?
B cell immunodeficiency
What causes autosomal Hyper-IgM Syndrome
Mutation in AID
What is the difference between X-linked Hyper-IgM Syndrome and autosomal Hyper-IgM Syndrome?
First one primarily affects men and second affects both men and woman
What causes Bare-Lymphocyte Syndrome?
Lack of MHC2 expression
What does Bare-Lymphocyte Syndrome cause?
T cell immunodeficiency
