Lab 2 Infection & Inflammation Flashcards
Erythrocyte sedimentation rate (ESR) principle
ESR measures the rate at which RBCs settle at the bottom of a vertically placed tube of anticoagulated blood over one hour. It is a non-specific marker of inflammation.
High ESR results suggest
High ESR indicates inflammation.
*Inflammatory conditions - high fibrinogen + ACPs - lower negative charge on RBC membranes.
* Cause RBCs to clump in stacks (rouleaux formation)
* Rouleaux are denser + settle faster = higher ESR.
ESR test method
- Place ESR tube in rack and pipette 1.5 mL whole blood into tube avoiding bubbles.
- Align 0 mark at top of scale with bottom with the bottom of the mensicus of blood.
- Read after 30mins.
White cell count vs differential white cell count
White cell count = total concentration of white blood cells
Diff. count = the percentage of each of the 5 types of mature white blood cells.
When does an elevated white cell count occur?
Infection, allergy, systemic illness, inflammation, tissue injury, leukaemia.
When does a low WCC count occur?
Viral infection, immunodeficiency states, bone marrow failure.
What are things that can interfere with WCC and diff counts?
Interference caused by
Small fibrin clots,
nucleated RBCs,
platelet clumping,
immature white cells,
unlysed RBCs.H
How to perform White cell count
- Pipette 380uL Turks fluid (haemolyses RBCs + stains WBCs) into a tube
- Pipette 20uL mixed blood sample into tube
- Place coverslip on haematocytometer
- Pipette 40uL into haematocytometer counting chamber.
- Allow cells to settle for 2mins.
- Using microscope on 10X count #cells in the 4 larger outside squares (which each consist of 16 smaller squares).
- Close condenser lens and adjust the light to visualize the stained white cells.
White cell count formula
N = #cells counted in the 4 outer squares
Blood was diluted 1:20
= (Nx20)/0.4 x 10^6 = x10^9 WCC/L
What does Romanosky stain?
Contains both red and blue stains.
Blue stain binds to acidic substances e.g. DNA in nucleus
Red stain binds to neutral + basic substances e.g. RBCs.
What consists of evalyating a blood film?
- Staining quality
- Is the nucleus purple, rbcs pink, granulocytes contain granules, platelets visible? - Red cell and Platelet comment
- Size/shape/colour of red cells (-cytic/-chromic etc.)
- Platelet abundance (thrombocytopenia/thrombocytosis) - WBC differential count
- % of each of the diff. immune cells in 100 cells
- neutrophils, lymphocytes, monocytes, basophils, eosinophils. - Comment and possible diagnosis.
How is infectious mononucleosis screening performed?
ACCUSAY Mono one-step antibody test
Using direct solid-phase immunoassay technology for qualitative detection of IM antibodies in human serum/plasma/blood.
- Pipette 25uL blood sample/ 10uL plasma/serum into upper end of sample well.
- Add 3 drops developer solution to lower end of sample well.
- Read test after 8 minutes (results stable for up to 15min).
How to recognize neutrophil?
Multi-lobed nucleus (2-5)
Pale pink/light blue cytoplasm
Fine light purple granules
Most abundant WBC
Involved in bacterial infections + inflammation.
How to recognize eosinophil?
Bi-lobed nucleus
Pink cytoplasm
Large orange-red granules
Involved in allergies + parasitic infections.
How to recognize basophils?
Bi-lobed or S-shaped nucleus
Purple cytoplasm
Large dark purple/black granules
Involved in allergies + histamine release.
How to recognize lymphocytes?
Small
Round, dense nucleus
Light blue cytoplasm
No granules
Involved in viral infections + immune responses.
How to recognize monocytes?
Kidney-shaped nucleus
Grey-blue cytoplasm
No granules
Largest WBC
Involved in phagocytosis, chronic inflammation.
What is infectious mononucleosis?
Infectious illness caused by EBV.
Lymphocytosis occurs with at least 10% atypical lymphocytes (large, irregular nuclei) on blood film
Symptoms include fever, pharyngitis, and swollen lymph nodes.
How to estimate platelet count when reviewing blood film?
Check feathered edge for platelet clumping.
Report abundance - platelets should be seen in every field of view (8-10platelets).
