immunodeficiency Flashcards
what is immunodeficiency?
- occurs when one or more two components of the immune system are defective
- you can’t start acute inflammation
what are the two types of immunodeficiency?
. primary
. secondary
what is primary immunodeficiency?
- caused by mutations in genes that produce proteins involved in immune response
- caused by mutations affecting genes that control expression and activity of immune responses
- often present from very young age
what is secondary immunodeficiency?
- acquired
- present at any age
1. consequence of other diseases
2. secondary to environmental factors (i.e. starvation/malnutrition)
3. an adverse consequence of medical intervention
e. g. steroids which induce immunodeficiency
how does immunodeficiency get diagnosed?
. patients with immune deficiency are usually detected clinically by a history of repeated infections with the same or similar pathogens this indicates immunodeficiency
what does the type of infection indicate?
. the type of infection indicates where the defect is in the immune system
what does it mean if you have repeated infection by pyogenic/pus forming bacteria?
. defect in antibody
. defect in complement system
. defect in phagocytic activity
e.g. macrophages aren’t working properly
what does it mean if you have a persistent fungal skin infection (cutaneous candidiasis ) or recurrent viral infection?
. defect in host defence mediated by T lymphocytes
what are the 5 ways of determining the competency of the immune system to diagnose the type of immunodeficiency?
- take a blood smear/sample to look for differences in white blood cell populations
- use fluorescent tags to target specific protein on the cell surface of each of white blood cells, this is called fluorescent activated cell sorting
- measurement of serum immunoglobulins (IgG)
- phagocytic competence leukocytes and monocytes
- complement activity is determined by testing the dilution of serum required for the lysis of 50% of antibody coated red blood cells
what is primary immunodeficiency caused by?
. caused by recessive genes which can be carried through generation
why is primary immunodeficiency more prevalent in males?
. recessive genes required two copies to be present to see a phenotype
. males who inherit a defective chromosome will manifest a disease
. females who have two X chromosomes will not show but are carriers
. rare occasions two defective genes inherited from heterozygous parent and show phenotype
. males have nothing in the y chromosome to counteract the mutation
why is primary immunodeficiency rare?
. because people who have display the phenotype will not live long to pass it on
what does primary immunodeficiency result in?
. low antibody levels
. defects in complement
. defect is phagocytic cells
. defects in T cells
what would happens as a result of low antibody level?
- low antibody levels will prevent opsonisation - innate immune systems isn’t particularly functional
- pyogenic bacteria - glycocalyx not recognised as foreign by receptors on macrophages and neutrophils to induce phagocytosis directly
. this means that bacteria escape immediate elimination by innate immune response
. eradicating bacteria requires antibody and complement opsonisation of the bacteria
what are the two ways that low antibody levels can happens?
- failure in antibody production from B-lymphocytes
e. g. XLA - failure in B cell receptor activation, so no switch between IgM production to IgG, IgE or IgA in B lymphocytes
e. g. patients with hyper IgM syndrome
where is IgM found?
IgM is found on cell surface of naive B cells
what does defects in complement components do?
. defects in complement affect pathogen destruction and self regulation
what is function of complement?
. pathogen destruction
. self recognition