Differential cell count
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1. The document describes the procedure for performing a differential white blood cell count using a modified battlement counting method. A blood film is prepared, stained with Giemsa stain, and examined under a microscope. 2. Using the modified battlement method, 100 cells of each type of white blood cell (basophils, eosinophils, neutrophils, monocytes, lymphocytes) are counted and their percentages calculated to aid in monitoring peripheral cell health. 3. The results are used to identify conditions related to increases or decreases in different white blood cell types, such as neutropenia, lymphocytosis, and monocytosis, which can indicate issues like infections, cancers, or bone marrow damage.
Differential cell count
- 1. Author: Negash Alamin Occupation: Clinical labscientist E-mail: [email protected] Date: 24/12/17
- 2. Principle: A routine blood film is made and it is stained by the usual Giemsa stain and is analyzed for blood cell morphology and the types of cells counted using modified battlement method. The differential cell count aids as an additional means of monitoring peripheral cell health and morbidity within the parameter of complete cell count. The counting methodology proceeds via the modified battlement method as stated above and a total of 100 cells of each type are counted and their percentage is calculated. Materials: 1- Gloves as PPE. 2- Frosted slide. 3- Micropippette. 4- Anticoagulated venous blood. 5- Staining reagent like Giemsa stain. 6- Differential WBC counter or alternatively we can use a labeled paper with each type of WBC and a pencil. 7- Compound microscope. Procedure: 1- First prepare a blood film and air dry for staining. 2- Fix the smear with methyl alcohol (methanol) for 3-5 minutes. 3- Flood with the diluted1 stain and wait for 15 minutes. 4- Wash off with distilled water and examine with oil emersion. 5- Using the modified battlement method start examining the blood cell morphology at the peripheral edge within the body of blood film by counting two fields parallel to the head of the film and four fields at right angle to the head of the film. 6- In doing so remember that you are moving in a zigzag fashion from the head to the tail counting all necessary 100 cells. 7- Finally you report your results in percentage of each WBC constituent. 1 The stock solution of Giemsa made up with 0.3 gm of Giemsa powder plus 25 ml of glycerol plus 25 ml of methanol is diluted for working solution by mixing 1 ml of stock solution with 9 ml of distilled water. (see Monica Cheesbrough book District laboratory Practice in Tropical countries page 404 reagent appendix for details of preparation)
- 3. Important points to remember: 1- When performing the count you do not just look for Basophils, eosinophil, neutrophils, monocytes and lymphocytes; but, for other pathological morphologies and parasites as well. 2- Look for size and maturation of WBCs, and RBCs. 3- Look for Toxic granulation, inclusions, vacuolation, hyper segmentation, malaria and other pathologies as well as abnormalities. 4- The absolute cell count of a single WBC can be counted and reported by multiplying its percentage for relative counts: example 60 % (0.6) neutrophil count by absolute WBC count 8.0 x /L which gives 4.8 x /L or 4,800 cells per microliter of blood.
- 4. Table 1 Absolute WBC hematological reference values2 Total absolute WBC 4.5 -11.0 x /L Or 4,000 to 11,000/µL Neutrophil 2.0 -7.5 x /L Or 2,000, to 7,500µL Lymphocyte 1.3-3.5 x /L Or 1,300-3,500µL Eosinophil 0-0.44 x L Or 0-440/µL Basophil 0-0.10 x / L Or 0-100/µL Monocyte 0.2-0.8 x /L Or 200-800/µL Clinical significance: The common terms used in clinical settings to refer to the conditions related with differential count and the increment or decrement of each WBC cell include neutropenia, neutrophilia, lymphopenia, lymphocytosis, monocytopenia, monocytosis, eosinophilia, and basophilia. These terms are medical terminologies whose suffix –penia indicate decrement and –philia or –osis indicate increment of each type of cell. The laboratory scientist will look for immature granulocytes (IG) like metamyelocytes, myelocytes, promyelocytes, and blasts to assess the health of the bone marrow overall cell production cascade in the body; if too much juvenile cells are present in the peripheral blood then there must be something pathology in the immuno-hematological system and this is very agenda of differential count. That is to observe cellular morphology like size comparison as in RDW, color, maturity and shape of every type of cell in the blood. Increase of neutrophils may occur due to: The routine culprit like infection with viruses, fungi, and bacteria. Tissue death or necrosis as in heart attack, and burns3 . Physiological stress and inflammation. Chronic leukemia Decrease of Neutrophils Autoimmune disorder Chemotherapy Cancer that spreads to the bone marrow 2 Oxford medical dictionary: 2010 3 Labtestsonline.org
- 5. Aplastic anemia4 Increase of lymphocytes Viral infections Lymphoma Decrease of lymphocytes Autoimmune disorders Chemotherapy and radiation Increase of monocytes Monocytic leukemia, chronic myelomonocytic leukemia, juvenile myelomonocytic leukemia5 Decrease of monocytes Bone marrow damage, hairy cell leukemia. . 4 Labtestsonline.org 5 Labtestsonline.org