Lab assessment of immunity Flashcards
What are three chemical/protein components of natural immunity?
complement, lysosome, and interferon
Which complement protein do all three pathways converge on?
C3. Which cleaves into C3a and C3b.
What is the net effect of the complement activation?
OIL
opsonization
Inflammation
Lysis
Describe the classical pathway
activated when IgM or IgG Ab’s bind to Ag’s on bacteria. C1 is what we start with.
Describe the alternative pathway
does not require presence of Ab or lectins
C3 binds to target
Describe the lectin pathway
similar to classical except no Ab’s, just lectin such as MBP
Activate C4 and C2
Why do we measure complement?
In cases of recurrent infection but normal WBC’s and no immunosupression.
To diagnose auto-antibody mediated immune syndromes, like autoimmune hemolytic anemia
To diagnose immune complex mediated syndromes such as Lupus, Sjorgren’s syndrome, glomerularnephritis
Expects to be low because we are using it up.
What are our two complement labs we can order
CH50 (classical)
AH50 (alternative)
What are some pathologies in which we see decreased levels of complement?
recurrent microbial infections (bacterial)
autoimmune diseases including SLE and vasculitis
hereditary angioedema
acquired angioedema
various types of kidney disease (including glomerularnephritis, lupus nephritis, membraneous nephritis, IgA nephropathy)
malnutrition
septicemia
serum sickness (immune complex disease)
Which labs could we order in suspected humoral/cellular immunodeficiencies?
IgG, A and M CBC with diff Lymphocyte subsets HIV test where indicated Humoral advanced investigations (IgG subclasses, specific Ab titers)
If you suspect cell mediated immunodeficiency, what labs can you order?
delayed type hypersensitivity skin tests, lymphocyte proliferation assays, and NK cytotoxicity
What are some common diagnostic tests ordered?
CBC with diff
Ab detection methods (IgM, IgG, IgA)
quantification and separation of Ig levels
testing for cell mediated immunity
