White blood cells (WBCs), also known as leukocytes, are present in organs, tissues, cells, and the immune system. They protect the body and its organs from infection at the tissue and cellular levels. WBCs are of different types. Differential Count (DLC) or a blood differential test helps find the number of immature or abnormal white blood cells in your blood. 

Differential Count (DLC) Test Overview 

White blood cells (WBCs), also known as leukocytes, are present in organs, tissues, cells, and the immune system. They protect the body and its organs from infection at the tissue and cellular levels. WBCs are of different types. Differential Count (DLC) or a blood differential test helps find the number of immature or abnormal white blood cells in your blood. 

Neutrophils, lymphocytes, monocytes, eosinophils, and basophils are the different types of white blood cells in the body. Out of them, the number of basophils is the least in the body. Despite being lesser in number compared to the other WBCs, they are of paramount importance for the body’s immune system. Whenever the immune system triggers a response, basophils release histamine and a bunch of additional chemicals that move through the blood vessels. 

The differential count provides a picture of different types of leukocytes present in the body. If there's a need to increase or decrease a specific WBC, it is possible with timely action. The test helps individuals take timely action and undergo treatment based on accurate test results. Other than the five different types of WBCs stated above, the results of DLC include other components. DLC test results indicate them both in terms of numbers and percentages. 

What is the purpose of Differential Count (DLC) Test? 

A general physical examination involves different tests. A blood differential test is one of them. It is directly related to the different types of WBCs in the body. Different WBCs perform different functions. The information about all of them in the body helps a healthcare provider gain an understanding of an individual’s state of health.

DLC includes the following test parameters: 
 

• Lymphocytes 
• Neutrophils 
• Eosinophils 
• Monocytes 
• Basophils 
• Absolute Lymphocyte Count 
• Absolute Neutrophil Count 
• Absolute Eosinophil Count 
• Absolute Monocyte Count 
• Absolute Basophil Count 

What does Differential Count (DLC) Test diagnose? 

A differential test is useful for diagnosing the following: 
 

• Infections 
• Different kinds of cancers, including leukaemia 
• Inflammatory diseases 
• Autoimmune diseases 

Why do you need Differential Count (DLC) Test? 

Your provider may recommend a DLC to find detailed information about your health condition. They will ask you to undergo the test for the following reasons: 
 

• For your overall health check-up 
• For the diagnosis of a medical condition 
• For monitoring a blood-related disorder 

Preparation and procedure for Differential Count (DLC) Test 

Unlike other tests, the differential count does not necessitate an individual to make any special preparation. The only thing required for the test is your informed consent for it. 

Understanding the results of Differential Count (DLC) Test 

The results of differential count tell whether you have leukaemia, anaemia, or any other kind of infection or not. Given below is detailed information about normal test results for the differential count. 

Normal results: You can consider your results normal if the different WBCs are present in your body in the following percentage: 
 

• Young neutrophil or band: 0% - 3% 
• Basophils: 0.5% - 1% 
• Eosinophils: 1% - 4% 
• Monocytes: 2% - 8% 
• Lymphocytes: 20% - 40% 
• Neutrophils: 40% - 60% 

What Do Abnormal Results Indicate? 

If there are higher-than-normal numbers of white blood cells in the body, it could be due to acute stress or an infection. Some other factors can also be responsible for it. These include leukaemia, an immune response, or inflammation. 

The problem with the higher number of specific white blood cells is that it reduces the number of other white blood cells. As a result, the percentage of such cells may decrease. It explains why it is necessary to have the right number of the different kinds of white blood cells in your body. 

Here’s a list of conditions that explain the higher and lower percentage of different white blood cells. 

Neutrophils: The following factors explain the reason for an increase in the percentage of neutrophils: 
 

• Cigarette smoking 
• Trauma 
• Thyroiditis 
• Rheumatic fever 
• Rheumatoid arthritis 
• Myeloproliferative diseases 
• Chronic or acute leukaemia 
• Gout 
• Eclampsia 
• Acute stress 
• Acute infection 

Your test result may show a reduced count of neutrophils due to the following factors: 
 

• Severe bacterial infection 
• Viral infection 
• Exposure to radiation or radiation therapy 
• Influenza 
• Chemotherapy 
• Aplastic anaemia 

Lymphocytes: The percentage of lymphocytes in the body can be due to the following factors:
 

• Viral infections like measles or mumps 
• Multiple myeloma 
• Lymphocytic leukaemia 
• Infectious mononucleosis 
• Infectious hepatitis 
• Chronic bacterial infection 

If you’re diagnosed with low lymphocytes in the differential count, it can be due to the following factors: 
 

• Sepsis 
• The use of steroids 
• Radiation therapy 
• Leukaemia 
• HIV/AIDS infection 
• Chemotherapy 

Monocytes: An increased number of monocytes may be due to the following factors: 
 

• Viral infections like measles, mumps, and mononucleosis 
• Tuberculosis 
• Parasitic infection 
• Leukaemia 
• Chronic inflammatory disease 

Eosinophils: When the number of eosinophils increases in the body, it is due to one of the following factors:
 

• Parasitic infection 
• Hyper eosinophilic syndromes 
• Collagen vascular disease 
• Chronic myelogenous leukaemia 
• Cancer 
• Allergic reaction 
• Addison disease 

Basophils: The percentage of Basophils increases in the body due to the following factors: 
 

• Chickenpox 
• Myeloproliferative diseases 
• Collagen vascular disease 
• Chronic myelogenous leukaemia 
• Allergic reaction 
• After splenectomy 

The following factors explain the reduced number of basophils in the body: 
 

• Acute infection 
• Severe injury 
• Cancer