The full form of TLC is Total Leukocyte count. It is done to count white blood cells (WBC) or leukocytes. These leukocytes are part of our body's defense system that fights off incoming infection to keep us fit and healthy. TLC is one of the tests that is done as part of the complete blood count test, which is the main test to evaluate the overall health of our body.
Definition
A total leukocyte count or white blood cell count is a blood test used to count white blood cells in the body. White blood cells are known as leukocytes (leuk means "white" and cyt means cell) and are an important part of our immune system. This helps fight infections caused by bacteria, viruses and germs. WBCs originate in the bone marrow and circulate in the blood.
Types
There are five main types of leukocytes, they are as follows:
- Acidophils/eosinophils (2-4%)- Number fluctuates during the menstrual cycle and during the day. It increases in response to allergies, collagen disease, central nervous system disease. They are rare in the blood. They mainly deal with parasitic infections and prevail in allergic reactions
- Basophils (0.5-1%) – They are mainly responsible for allergic reactions. They release chemicals like histamine to relax blood vessels. They are the rarest type of white blood cell and therefore difficult to study. They mainly secrete two chemicals – istamine and heparin They also create chemical signals that attract eosinophils and neutrophils to the site of infection
- Neutrophils (55-73%) – Neutrophils are the most abundant and the first responders to come to the defense during a bacterial or fungal infection. The average life cycle of a neutrophil cell is 5-153 hours.
- Monocytes (2-8%)- They share the functions of phagocytosis or vacuum cleaning with neutrophils. They live longer than neutrophils because they have other functions, such as delivering pieces of the pathogen to T cells. That they can recognize them and they are killed in the next invasion. Thus, they help in generating antibody-mediated responses. After leaving the bloodstream, they enter the tissue, where they act as tissue macrophages, removing cell debris and attacking microorganisms.
- Lymphocytes- It contains T cells and B cells and Natural killer cells (20-40%) They are common in the lymphatic system. Here, B cells make antibodies that block invading pathogens, and T cells are known as helper cells that help produce an army of antibodies against incoming infection. Natural killer cells, on the other hand, kill cells that do not display MHC class -1 molecules
Normal Range
A normal TLC range is around 4000 – 11000 cells/cubic millimeter of blood.
Low TLC count
A count of less than 4,000 cells/cubic millimeter of blood is below normal. A drop in the number of leukocytes is a sign of leukopenia, which will further reduce our ability to fight
A lower TLC count can be caused by:
- Lack or failure of bone marrow due to infection or tumor
- Medicines to treat cancer or other medicines such as captopril, chemotherapy drugs, sulfonamides, chlorpromazine, ticlopidine
- Liver or spleen disease
- A serious bacterial infection
- Viral diseases such as mononucleosis
- Physical or emotional stress due to surgery
- Autoimmune diseases such as lupus
Higher number of TLCs
An increase in TLC is known as leukocytosis and is a sign of acute inflammation and infection. It can also be for the following reasons:
- Cigarette smoking
- Tissue damage
- Bacterial infections
- Spleen removal surgery
- Certain drugs or medicines like heparin, lithium, epinephrine, corticosteroids and other granulocyte stimulating factors.
- Leukaemia and Hodgkin’s disease
- Allergy or anY other inflammatory disease