White Blood Cell Differential.
The white blood cell differential classifies a person's white blood cells by breaking them down into each of the five types.
Three of these types are known as granulocytes and the other two as lymphoid cells.
The numbers of these cells are never static, they vary from day to day. However significant increases in one type or another will show up in different conditions, which may be temporary, or an acute or chronic. The results will give your doctor a better idea of what is going on.
How the test for these is done:-
a) Manual differentials
A drop of blood is spread on a slide, stained and then from 100 cells upward are examined for quality or any changes that may have occurred.
b) Automated differentials
Here instruments test either for particular compounds inside the cells or they compare the size, shape and the content of the cells.
They can count thousands of cells at a time.
Results are reported as percentages of the types of WBC present, or in absolute values, also called the Absolute Cell Count or ACC, which is achieved by multiplying the total white cell count by the percent of a specific cell reported.
Eg. - (Total WBC x % cell type) / 100 = absolute value.
Lets look at an example:-
Assume the WBC is 5000, the cell type is 38%
Therefore (5000 x 38) divided by 100 = 1900
The absolute value is thus 1900/µl (cells per microlitre of blood).
Percentages are okay for most people but if you have any type of blood disorder (hematologic disorder) it is necessary to know the absolute values.
The lymphoid cells
The two types are: lymphocytes and monocytes.
These are sometimes called agranulocytes because they do not appear to have any granules in the cytoplasm, which makes it appear transparent. The nucleus is more compact though it may occasionally be bi-lobed in monocytes.
Though they look similar they actually are produced in different places. Like granulocytes the monocytes are made in the bone marrow but the lymphocytes are produced in the lymphatic organs eg the thymus.
Lymphocyte
Adult Range: 18 - 40%
Absolute value or Absolute lymphocyte counts (ALC):
720- 4400/µl or 0.72 - 4.4 x 10*9/L.
Children's Range: 25 - 50%
Absolute value or Absolute lymphocyte counts (ALC):
1000 - 5500/µl or 1.0 - 5.5 x 10*9/L.
Monocyte
Adult Range: 3 to 8%
Absolute value or Absolute monocyte count:
120 - 880/µl or 0.1 - 0.8 x 10*9/L.
The granulocytes.
The three types of granulocytes are: neutrophils, eosinophils, basophils. They are named because of their granules affinity for either neutral, acid or basic stains - in other words neutrophil granules colour with neutral stains, basophils with basic (or alkaline) ones and eosinophils with acid ones (eosin is an acidic stain).
Certain things are the same for all of them. They are produced in the bone marrow, they have a cytoplasm rich in granules, (which help microbiologists recognise them, because the granules take on specific colours when stained) and their nuclei have 2 or more lobes.
Neutrophils
Adult Range: 50 - 73%
Absolute value or Absolute neutrophil counts (ANC):
2,000 - 8,030/µl or 2.0 - 8.0 x 10*9/L.
Children's Range: 30 - 60%
Absolute value or Absolute neutrophil counts (ANC):
1200- 6600/µl or 1.2 - 6.6 x 10*9/L
Eosinophils
Adult Range: 2 - 4%
Absolute value:
80 - 440/µl or 0.08 - 0.4 x 10*9/L.
Basophils
Adult Range: 0.5 - 1%
Absolute value:
20 - 110/µl or 0.02 - 0.1 x 10*9/L.