Lecture 12 - Lab Assesment Flashcards
Why should lab investigations be interpreted with caution
- current infection
- stage of infection
- age
- co-morbidities
What are acute phase proteins
- CRP
- Mannose binding Lectin
- alpha1-antitrypsin
- fibrinogen
- complement proteins (C3, C4)
- haptoglobin
- ceruloplasmin
What happens to albumin as acute phase proteins increase
it decreases
What causes increased acute phase proteins
- infections
- autoimmune disease
- trauma, surgery, burns
- tissue infarction
- malignancy
- radiation therapy
What induces increased acute phase proteins
TNF, IL-6, IL-1
What is CRP
- it binds C-polysaccharide of S. pneumonia and other bacteria, fungi and parasites
- can activate complement without antibodies
- can bind and clear toxins from damaged tissue
- levels rise after onset of inflammation
- can be used to monitor inflammation and malignancy
What is the reference range of CRP
<8.0 mg/L
What is hsCRP
an indicator of cardiovascular disease/stroke
What is a limitation of hsCRP
if CRP is increased hsCRP will be beyond the limit of linearity and cannot be used
How do we measure neutrophils quantitatively
using a CBC differential (absolute count)
How do we measure neutrophils semi-qualitatively
- toxic changes
- left shift (blasts/immature)
How do neutrophils support the immune system
NADPH Oxidase is produced in response to TNF, IL-1, thrombin, PDGF, phagocytosis
How to test the function of neutrophils
neutrophil oxidative burst test
How does the neutrophil oxidative burst test work
- collect patient neutrophils
- incubate with DHR123
- add mitogen which stimulates NADPH oxidase production
- H2O2 oxidizes DHR123 which fluoresces with rhodomine
- the increase in fluorescence is seen after treatment by flow
How to test neutrophil adhesion
CD11 and CD18 quantitated by flow cytometry
How to test neutrophil chemotaxis
- can look at receptor (IL-8)
- can look at movement using a boyden chamber
How does a boyden chamber work?
- IL-8 is added to the bottom of the chamber
- a mesh membrane is put between two gel layers with buffy coat added on top
- migration through the gel results in cells caught on the membrane and examined microscopically
What are quantitative methods for lymphocytes
- CBC differential
- Tcells: CD3, CD4, CD8
- Bcells: CD19
- NKcells: CD16/CD56
What are qualitative methods for B cell analysis
- antibody levels (GAM)
- IgG subclasses
- specific antibodies (ABO, expected antibody titres, titre pre/post vaccination)
What are qualitative methods for T cell analysis
- in vitro
– t activation
– clinical correlation B response (infections) - in vivo
– delayed type hypersensitivity test (ie. tuberculosis skin test)
– sensitization phase (activation of Th1 cells)
– effector phase ( antigen exposure, activate monocytes, neutrophils)
How does the tuberculosis skin test work
- purified protein derivative tuberculin is injected under the skin
- 48-72 hour response
- positive means exposure to tuberculosis or vaccine
What other organisms could the tuberculin skin test apply to
- tetanus toxoid
- candida albicans
What are the phases of the delayed type hypersensitivity test
- Sensitization
- Effector
How to test complement
- C3, C4 quantitation are routine
- CH50 test requires all components to function
How does the CH50 test work
- liposomes contain glucose-6-phosphate dehydrogenase
- liposomes also have DNP on their surface
- ant-DNP is added to patient serum
- patient complement forms the membrane attack complex and releases G6PDH
