Lab Asessment Of Immune System Flashcards
Why should lab investigations for the immune system be interpreted with caution ?
current infections can use up circulating proteins and antibodies = false low
Albumin __ as Acute Phase Proteins __
Albumin DECREASE as Acute Phase Proteins INCREASE
List Acute Phase Proteins (7)
- C-Reactive Protein (CRP)
- Mannose binding Lectin
- α1-antitrypsin
- Fibrinogen
- Complement Proteins (C3, C4)
- Haptoglobin
- Ceruloplasmin
Conditions that increase Acute Phase Proteins
- Infections (bacterial, viral, parasitic)
- Autoimmune disease
- Trauma, surgery, burns
- Tissue infarction (myocardial, renal)
- Malignancy
- Radiation Therapy
NOTE: Induced by TNF, IL-6, IL-1 from leukocytes
Describe CRP
- Binds C-polysaccharides of S. pneumonia and
other bacteria, fungi, and parasites
- Bind & clears toxins from damaged tissue - can activate complement without Ab
- levels rise after onset of inflammation (4-12 hrs)
- used to monitor inflammation AND malignancy
What does it mean if neutrophils are showing a left shift ?
Colony Stimulating Factor is inducing bone marrow to produce more cells
NADPH Oxidase in neutrophils is produced in response to: (5)
- TNF
- IL-1
- thrombin
- PDGF
- phagocytosis
Purpose of NADPH Oxidase
- NADPH reacts with oxygen and NADPH oxidase to generate super oxides
- super oxides lead to other reactive oxidative species ie. hydroxyl, hydrogen peroxide, hypochlorite
Describe Neutrophil Oxidative Burst Test
- collect patient neutrophils
- incubate with colorless DHR123 (indicator)
- add mitogen: irritate cells to produce NADPH = superoxides
- hydrogen peroxide oxidizes DHR123 = Rhodamine (fluorescence)
Tests to assess whether neutrophils are able to exit circulation and enter site of infection
- Flow cytometry (CD11 and CD18): integrins that bind to ICAM so neutrophils can roll and exit circulation
- chemotaxis/ phagocytosis kits: patient neutrophils respond to IL-8 and move using Boyden chamber
How are lymphocytes differentiated ?
- CBC + diff
- Flow cytometry: T cells (CD3) vs B cells (CD19) vs NK (CD16/ CD56)
How is B cell quality assessed ?
- antibody titre levels (IgM, IgG, IgA)
- specific antibodies (ABO)
How are T cells assessed qualitatively ?
Delayed type hypersensitivity test
1. Sensitization phase = activation of Th1 (measure Th17, T cytotoxic, NK cells)
2. Effector phase = exposure to antigen = Th1 secrete IFN-γ, TNF-β = activates monocytes, neutrophils
Describe Delayed type hypersensitivity test
- purified protein derivative (tetanus toxoid, C. albicans) tuberculin injected under skin
- takes up to 3 days to respond
- POS = previous exposure to tuberculosis or vaccine
How is complement assessed ?
- quantitate C3 and C4
- CH50 DNP test
Describe the CH50 DNP test
- ensures all complement proteins are present and functioning (qualitative)
- DNP on liposome acts as antigen
- patient plasma = source of complement
- anti-DNP added = binds DNP = classical pathway activated = MAC lyses liposome and releases G6P = NADH absorbance is measured
