Calculating Absolute Cell Counts

How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 180 CE courses, most popular
$109Add to cart
Pick Your Courses
Up to 8 CE hours
$55Add to cart
Individual course$25Add to cart
The page below is a sample from the LabCE course Introduction to Flow Cytometry: Blood Cell Identification. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Introduction to Flow Cytometry: Blood Cell Identification (online CE course)
Calculating Absolute Cell Counts

Lymphocytes are a specific type of white blood cell. They can be T cells or B cells. In the mature T cell population, lymphocytes can be helper T cells or suppressor/cytotoxic T cells.
Understanding the principles behind the identification of these T cell populations is essential. To begin, CD3 marks all mature T cells. Then:
  • CD4 marks T-helper cells
  • CD8 marks cytotoxic T cells
Therefore, in any given lymphocyte population, the CD4+ and CD8+ cells should equal the CD3+ cells. Since the CD4 and CD8 cells are both mature T cells, they will be marked with CD3.
Provided with the total white blood cell (WBC) count and the percentage of lymphocytes from a complete cell count/differential, various values can be calculated. These values include absolute CD3 counts, CD4 counts, CD8 counts, and CD4:CD8 ratios.
The following results represent a patient sample that is used to calculate the values above:
WBC count = 2.5 x 103/mcL (2500 cells/mcL)
% Lymphs = 30%
Using the following calculation: Absolute (Abs) lymphs = WBC count x 1000 x percent lymphs (expressed as a decimal), we can determine the absolute lymphocyte count per mcL.
2.5 x 1000 x 0.30 = 750 lymphs/mcL
*Note: mcL = microliter