08 Feb

Differential White Blood Cell Count

A differential white blood cell count is used to determine the relative percentages of various types of cells within a blood sample.  Elie Metchnikoff proposed the theory of phagocytic immunity at the Pasteur Institute in 1883.  He stated that large cells in the blood stream are responsible for defense against bacterial infections.  Neutrophils, eosinophils, basophils, lymphocytes, and monocytes are the five types of cells in the blood responsible for engulfing foreign bodies in the blood.  Wright’s stain is used to make these cells more visible under the microscope.  When these cells are not stained they are colorless structures.  During a differential white blood cell count 100 cells are counted using a differential counter and the percentage of each type of cell is determined.  Neutrophhils are typically the most abundant making up 50-70% of the sample.  There are between 5,000 and 10,000 white blood cells per cubic millimeter in a normal white blood cell.