L26-Immunodeficieny and the immunology laboratory Flashcards
what should make a doctor suspect immunodeficiency?
Recurrent infections and infections that take longer than normal to treat.
What is the difference between primary and secondary immunodeficiency?
Primary immunodeficiency is when it is inherited or due to polymorphisms.
Secondary immunodeficiency is when a disease causes the deficiency such as HIV
What are the main mechanisms that will result in a failure to produce antibodies?
A failure to produce B cells
A failure in T helper cells so B cells cannot produce high affinity antibody
A failure to class switch
When do antibody deficiencies tend to present themselves in life?
After 6 months as this is when maternal IgG antibodies wear off. Often occur as recurrent respiratory tract infections.
How does common variable immunodeficiency tend to present and when?
Tends to present in adulthood as it is linked to a genetic cause that is triggered by a second factor such as an infection.
How is antibody deficiency treated?
Immunoglobulin replacement therapy from donors
How is T cell deficiency often seen?
Characterised by increasing susceptibility to ‘opportunistic infections’. These result in regular infections from organisms that would not normally infect individuals that weren’t immunocomprimised.
What are severe T cell deficiencies categorised into?
Severe combined immunodeficiency (SCID)
What does neutrophil deficiency result in?
Severe invasive bacterial infections that respond poorly to antibiotics.
Give two examples of neutrophil disorders?
Congenital neutropenia-low neutrophil numbers
LAD- results in increased numbers of neutrophils in the blood during infections but none in the tissues (absence of pus)
What does a low C3 suggest a problem with?
A defect in either the alternative or classical pathways.
What does a low C4 suggest a problem with?
A classical pathway problem
What does C1 esterase inhibitor deficiency cause and what is the result of this?
Causes hereditary angioedema which presents with recurrent spontaneous attacks of oedema
Needs to to treated with C1 esterase inhibitor replacement
What are deficiencies of the terminal lytic pathway of complement (C5-9) characteristic of?
Increased risk of infection from meningitis and gonorrhoea
What are the two tests for neutrophils?
Full blood count
Oxidative burst
