Question

1. Suppose you were to separate 5 ml of blood and have a 65% recovery of the white blood cells. Suppose further that 80% of those cells were viable. You resuspend the recovered cells in 10 ml of media (RPMI + FCS, keeps the cells from blowing up). You then dilute them 1:10 in the same medium, and follow the protocol for Trypan blue staining. Based on what you know of the percentage of white blood cells in blood, how many cells would you expect to see on average in each counting square of the hemocytometer. Show your work and explain where you got your starting value.

2. What is it that causes sheep red blood cells to form rosettes with T-cells? How many T-cell rosettes do you expect to see in a second sample from the sample you collected in question 1?

assume the WBC count in the blood is 5,000 cells per micro liter

Answer 1

Answer 1:)

Suppose a concentration is present in the 5 ml of the blood.

65% of white blood cell = a x 65%

65% of white blood cell = 0.65a

The 80% viable cells of 0.65a = 0.65a x 80%

The 80% viable cells of 0.65a = 0.52a

0.52a cells diluted by 10-1 factor, concentration of these cells in the 10 ml media; therefore, the concentration = 0.52a x 10-1

Suppose 20 uL is spread on the hemocytometer;

20 uL in ml = 20 x 10-3 mL

20 uL in ml = 0.02

Concentration of cells in 20 uL = 0.52a x 10-1 / 0.02

Concentration of cells in 20 uL = 26a x 10-1

Concentration of cells in 20 uL = 2.6a

Therefore, at the hemocytometer, 2.6a number of cells will be found.