Lab 2. Cells of the Immune System
Peripheral Blood Smear

Procedure:

1. Clean a microscope slide with 70% ethanol and lens paper.

2. Spray your left "ring " finger with 70% ethanol or wipe it with an alcohol wiper and let it air dry.

3. Take a sterile lancet and puncture your fingertip.  If you have calluses, aim a little to the side. DO NOT LANCET ANYONE OTHER THAN YOURSELF.  When finished with your lances, place them in the BIOHAZARD CONTAINER.

4. Place a small drop of blood on the end of the slide.  At this point, put on GLOVES.  DO NOT TOUCH ANYONE ELSE’S BLOOD.

5. Now you need to spread the blood out so that a single layer of cells is obtained.  To do this, take a new “spreader” slide and place it in the center of you “blood” slide.  Move it toward the drop of blood.  When it contacts the drop, the blood will spread out along the edge of the “spreader” slide.  Now comes the hard part.  With a smooth motion, push the “spreader” slide back about 3/4 of the way toward the other side of the “blood” slide.  This will pull the blood along with it.

6. Let the smear dry thoroughly.

7. Stain the smear with Wright stain as described on the accompanying sheet.

8. Let the smear dry thoroughly.

9. Examine the smear.  Most of what you will see are red blood cells, but don’t count these.  Count as many white blood cells as you can categorize as indicated on the figures below, with about 100 giving a good differential count.  Record the number and percent of :
 
 

Cell Type Cell Number %
Neutrophils    
Lymphocytes    
  Monocytes    
Eosinophils    
Basophils    
Total   100

10.  Dispose of slides in the BIOHAZARD waste.


Smear of human peripheral blood stained with Wright's stain.

Human Peripheral Blood Cells


Cell Type
Cells/ml blood (%)
Function
Erythrocytes
6,000,000
Oxygen transport
Platelets
300,000
Blood clotting and blood vessel repair
Neutrophils
5,000 (50-70%)
Phagocytosis
Lymphocytes
3,000 (20-30%)
Specific immunity
Monocytes
500 (2-6%)
Phagocytosis and present antigens
Eosinophiles
300 (1-5%)
Destroy antibody-antigen complexes
Basophils
30 (<1%)
Unknown

 


Lymphocytes function in specific immunity

Reading
Immunobiology 1-1

Study Questions

1. What is the most numerous type of leukocyte in human blood? What is this cell’s primary function?

2. Were your percentages for human blood within the expected ranges?

3. State the name and function of each of the following cells.