Immunology 2 - Primary immune deficiencies parts 1 & 2 Flashcards
Recall 3 infections that can cause immunodeficiency
HIV
Measles virus
Mycobacterial infection
Recall 3 diseases of neutrophil deficiency
Reticular dysgenesis
Kostmann syndrome
Cyclic neutropenia
What is the cause of Leukocyte adhesion deficiency?
CD18 deficiency - failure to express this ligand means they cannot exit the bloodstream
What will be the most obvious abnormal result on the blood count in leukocyte adhesion deficiency?
Very high neutrophils (they cannot exit the bloodstream)
What is chronic granulomatous disease?
A failure of phagocytic oxidative killing mechanisms
Recall 2 tests that are useful in the investigation of chronic granulomatous disease
- Nitroblue tetrazolium test (negative = blue, positive = yellow)
- Dihydrohodamine flow cytometry test (negative = fluorescent)
Which innate immunodeficiency is characterised by severe chickenpox and disseminated CMV infection?
Classic Natural Killer cell deficiency
Which innate immunodeficiency is characterised by recurrent infections with hepatosplenomegaly and abnormal dihydrohodamine test (does not fluoresce)?
Chronic granulomatous disease
Which innate immunodeficiency is characterised by recurrent infections with no neutrophils on FBC?
Kostmann syndrome
Which innate immunodeficiency is characterised by infection with atypical mycobacterium, and a normal FBC?
IFN gamma receptor deficiency
Which innate immunodeficiency is characterised by recurrent infections with high neutrophil count on FBC but no abscess formation?
Leukocyte adhesion deficiency
With which innate immunity deficiency is meningococcal septicaemia associated?
Deficiency of complement (C1q)
With which innate immunodeficiency is membranoproliferative nephritis and abnormal fat distribution associated?
C3 deficiency with presence of a nephritic factor
What mutation is causative of X-linked SCID?
Common gamma chain on chromosome Xq13.1
Describe the phenotype of X-linked SCID in terms of T, B and NK cell numbers
T cells: very low or absent
B cells: Normal or increased B cells, but LOW Igs
NK cells: very low or absent
How does adenosine deaminase deficiency affect the immune system?
This enzyme is necessary for cell metabolism in lymphocytes.
When it is deficient, there is early arrest of T and NK cell development and production of immature B cells.
Describe the phenotype of ADA deficiency in terms of T, B and NK cell numbers
All very low or absent
Describe the clinical phenotype of SCID
- Unwell by 3 months of age
- Infections of all types
- Failure to thrive
- Persistent diarrhoea
- Unusual skin disease
- Family history of early infant death
What is the gene mutation implicated in DiGeorge syndrome?
22q11.2 deletion
How does DiGeorge syndrome affect B and T cell levels?
Normal B cells
Reduce T cells
What is bare lymphocyte syndrome type 2?
Absent expression of MHC class II causing severe deficiency of CD4+ T helper cells –> results in low IgG OR IgA
What inherited immunodeficiency might cause a profound deficiency of CD4+ T cells specifically?
Bare lymphcoyte syndrome type 2
What is reticular dysgenesis?
Failure of stem cells in BM to differentiate along myeloid or lymphoid lineage
What is Kostmann syndrome?
Failure of neutrophils to mature - causes a congenital neutropenia
What is cyclic neutropaenia?
Autosomal dominant episodic neutropenia every 4-6 weeks
What are the features of chronic granulomatous disease?
Absent respiratory burst, leading to:
- Excessive inflammation
- Granuloma formation
- Lymphadenopathy
- Hepatosplenomegaly
What immunodeficiency are recurrent skin and mouth infections most likely to be indicative of?
Phagocyte deficiency
Which phagocyte deficiency has absent neutrophils and normal leukocyte adhesion molecules?
Kostmann syndrome
Which phagocyte deficiency has absent CD18 and increased neutrophils?
Leukocyte adhesion deficiency
Which phagocyte deficiency has normal neutrophil levels and leukocyte adhesion markers, an abormal NBT/DHR test and pus is produced?
Chronic granulomatous disease