immunodeficiencies Flashcards
what is immunodeficiency
caused by defects in one or more components of the immune system
may lead to serious and often fatal syndromes or diseases
primary/secondary
data difficult to estimate as no current screening program at birth exists
classification - primary immunodeficiencies
condition resulting from a genetic or developmental defect
the defect is present from birth and is mostly inherited
may not be clinically observed until later in life
abbreviated as PID
secondary immunodeficiencies
originate as a result of malnutrition, cancer, drug treatment or infection
by far most well known and common is AIDS
clinical features of primary immunodeficiency
recurrent infections
severe infections, unusual pathogens
10 warning signs 2 or more could indicate PID
- failure of kid to grow normally
- need for intravenous antibiotics to treat infections
- history of PID in family
cause of primary immunodeficiences
affect innate or adaptive immune function
defects in innate immunity are caused by defect in phagocytic or complement function
lymphoid cell disorders may affect t cells or b cells or both
haematopoiesis and PID
consequences of defect depend on number and type of immune system components involved
defects in earlier stem cells affect entire immune system
defects in later stage haematopoietc cells show a more restricted pathology
PID - defects in adaptive immunity
b and t cells
often t cell defects impair antibody production
defects in lymphocyte development or activation
pid - MAJOR b cell disorders
x linked agammaglobulinaemia common variable immunodeficiency selective igA deficiency igG2 subclass deficiency specific ig deficiency with normal Igs
what is x linked agammaglobulinameia
aka as bruton's disease defect in BTK gene encodes brutons tryosine kinase block in b cell development recurrent severe bacterial infections 2nd half of first year autoimmune disease
needed for pre-b cell receptor signalling.
result block in B-cell development at pre-B stage
diagnosis of x-linked agammaglobulinaemia
b cells absent
all immunoglobulins absent
t cells and t cell mediated response normal
treatment
- IVIg = 200-600mg/month
prompt antibiotic therapy
selective IgA deficiency
most common
most cases asymptomatic
low level serum and secretory iga
PID : combined immunodeficiencies
severe combined immunodeficiency = SID
predominant T cell disorder
digeorge syndrome
wiskott-aldrich syndrome
ataxia-telagiectasia
SCID causes
common cytokine receptor gamma chain defect
IL-7 needed for survival t cell precursors resulting in defective t cell development and concomitant lack in B cell help
RAG1/2 defect = no t/b cells
patients must isolate and be in a sterile enviroment
cant recieve live vaccines
blood products from CMV- negative donors
stem cell transplant
digeorge syndrome
thymic hypoplasia due to 22q11 deletion
results in failure development 3+4th pharyngeal pouches \
array of defects
dysmorphic face = cleft palate, low set ears, fish shaped mouth
hypocalcaemia, cardiac abnormalaties
variable immunodeficiency
treatment
thymus transplant
