Immunodeficiency Flashcards
What are the clinical features associated with immunodeficiency?
Chronic infection Recurrent infections (more than expected) Unusual microbial agents Incomplete clearing of infection Incomplete response to treatment
What are the types of immunodeficiency?
Primary
Secondary
Describe the features of primary immunodeficiency
Mostly genetically determined (from birth)
Involves intrinsic defects in
lymphocytes
complement components
or phagocytic cells
Specific (abnormalities of B or T cells) or non-specific (deficiency in innate components)
The type of infection can indicate which part of the immune system is immune deficient.
What deficiencies are Pyogenic infections linked to?
Deficiencies in:
Phagocytosis
Complement
Antibody
The type of infection can indicate which part of the immune system is immune deficient.
What deficiencies are opportunistic infections linked to?
Defects in cell-mediated immunity
Give examples of pyrogenic infections
Streptococcus pneumoniae
Haemophilus influenzae
Staphylococcus aureus
What symptoms are pyrogenic infections linked to?
Pneumonia, sinusitis, otitis media
Give examples of opportunistic infections
Gut parasite- Giardia lamblia
Candida albicans
Chickenpox
What symptoms are opportunistic infections linked to?
Diarrhoaea, common yeast & viral infections
What is the most common inheritance pattern of congenital primary immunodeficiencies?
X-linked
Give examples of X-linked congenital primary immunodeficiencies
Chronic Granulomatous Disease (CGD) Wiskott-Aldrich Syndrome (WAS) Severe Combined Immunodeficiency (SCID) X-Linked Agammaglobinaemia (X-LA) X-Linked Immunodeficiency with High IgM (HIgM)
What can cause congenital primary immunodeficiencies?
The cause of a primary deficiency may vary
Mutations – rare, affect any part of immune system, cause severe disease
Polymorphisms – very common, moderate increased risk of infection
Polygenic disorders- relatively common, affect mainly antibodies, usually cause severe disease
Describe the features of polymorphisms for congenital primary immunodeficiencies
Multiple alleles of the same gene occurring at a single locus -in at least 1% of population
Polymorphisms in promoter for TNF – susceptibility to cerebral malaria, septic shock
Chemokines & receptors – susceptibility to HIV
Mannan binding lectin & complement components – susceptibility to fungal and bacterial infections
TLR polymorphisms – susceptibility to various infections
Describe the features of polygenic disorders for congenital primary immunodeficiencies
Involves interaction of several genes + environmental factors
CVID, 1 in 20,000 people – mild to severe
IgA, IgG subclass deficiencies - moderate
IgA deficiency, 1 in 700 people - mild
IgG2 deficiency – moderate (pneumococcal, haemophilus infections)