Lab Asessment Of Immune System

Question 1

Why should lab investigations for the immune system be interpreted with caution ?

Answer 1

current infections can use up circulating proteins and antibodies = false low

Question 2

Albumin __ as Acute Phase Proteins __

Answer 2

Albumin DECREASE as Acute Phase Proteins INCREASE

Question 3

List Acute Phase Proteins (7)

Answer 3

• C-Reactive Protein (CRP)
• Mannose binding Lectin
• α1-antitrypsin
• Fibrinogen
• Complement Proteins (C3, C4)
• Haptoglobin
• Ceruloplasmin

Question 4

Conditions that increase Acute Phase Proteins

Answer 4

• 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

Question 5

Describe CRP

Answer 5

• Binds C-polysaccharide of S. pneumonia and
  other bacteria, fungi, and parasites
• can activate complement without Ab
• bind / clear toxins from damaged tissue
• levels rise after onset of inflammation (4-12 hrs)
• monitor inflammations AND malignancy

Question 6

What does it mean if neutrophils are showing a left shift ?

Answer 6

Colony Stimulating Factor is inducing bone marrow to produce more cells

Question 7

NADPH Oxidase in neutrophils is produced in response to: (5)

Answer 7

• TNF
• IL-1
• thrombin
• PDGF
• phagocytosis

Question 8

Purpose of NADPH Oxidase

Answer 8

• NADPH reacts with oxygen and NADPH oxidase to generate super oxides
• super oxides lead to other reactive oxidative species ie. hydroxyl, hydrogen peroxide, hypochlorite

Question 9

Describe Neutrophil Oxidative Burst Test

Answer 9

• collect patient neutrophils
• incubate with colorless DHR123
• add mitogen: irritate cells to produce NADPH = superoxides
• hydrogen peroxide oxidizes DHR123 = Rhodamine (fluorescence)

Question 10

Tests to assess whether neutrophils are able to exit circulation and enter site of infection

Answer 10

• CD11 and CD18 quantitation via flow cytometry: 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

Question 11

How are lymphocytes differentiated ?

Answer 11

• CBC + diff
• Flow cytometry: T cells (CD3) vs B cells (CD19) vs NK (CD16/ CD56)

Question 12

How is B cell quality assessed ?

Answer 12

• antibody levels (GAM)
• antibody subclasses (IgA vs IgG, IgM)
• specific antibodies (ABO, titres)

Question 13

How are T cells assessed qualitatively ?

Answer 13

• delayed type hypersensitivity test
• sensitization phase = activation of Th1 = difficult to measure [IL-2] directly = measure Th12, Tc NK cells instead
• effector phase = exposure to antigen = Th1 secrete IFN-γ, TNF-β = activate monocytes, neutrophils

Question 14

Describe Delayed type hypersensitivity test

Answer 14

• 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

Question 15

How is complement assessed ?

Answer 15

• quantitate C3 and C4
• CH50 DNP test

Question 16

Describe the CH50 DNP test

Answer 16

• 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