Lymphocytes – Normal Range, High, Low (Causes)

Lymphocytes are white blood cells that are found in the blood and are vital in the immune system of the body. White blood cells protect our bodies from diseases by fighting against infections. When foreign microorganisms that are likely to cause diseases enter the body, the lymphocytes respond immediately by attacking the infectious agents and toxins.

Microorganisms are very tiny organisms that can only be seen under the microscope. Even so, lymphocytes can detect such tiny microorganisms and respond immediately. They also prevent abnormal growth of cells and tumors. They also determine self and foreign body tissues. This can cause tissue rejection during tissue transplants, which could result in an adverse reaction.

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Types of lymphocytes

There are three main types of lymphocytes, namely; natural killer cells, T cells, and B cells. T cells derive their name from thymus gland as it is the site where they are manufactured. The T cell receptor molecule is specialized and is the main component that distinguishes T cells from other types of lymphocytes. The T cell receptor is vital in recognizing antigens and binding on them.

B cells are also vital in the body’s immune system. They are produced in the bone marrow hence their name B cells. They are distinguished from other types of lymphocytes by B cell receptor, a protein which is found on their surface. The protein plays a vital role in recognizing and attaching to individual antigens.

Natural killer cells lymphocytes are cytotoxic; they have the ability to destroy other cells.  This property enables them to identify virally infected cells and tumors and kill them before they can spread and cause more harm in the body. It is this function that makes them a vital component of body’s immune system.


lymphocytes picture


Lymphocytes are small in size and are about seven to eight micrometers long. Larger types of lymphocytes have a length ranging from ten to twenty micrometers. Micrometers are very small units of measurements. This means these blood cells are very small in size. They have a nucleus, which forms the central structure. The nucleus consists of thin threads that turn blue or purple when stained with a dye called Wright’s stain.

Lymphocytes are different from other kinds of white blood cells such as eosinophils and basophils in that they do not have big, grain-like and rough looking particles. Large types of lymphocytes have much cytoplasm and are made up of grain-shaped, reddish or purplish, rough looking particles. While other cells turn blue in color in the presence of various chemicals during laboratory tests, lymphocytes do not.

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High level of lymphocytes – Causes

An abnormally high level of lymphocytes is associated with viral infection. In some instances, raised lymphocyte counts lead to leukemia. A high count of these cells beyond normal range is considered abnormal and not healthy as it could generate other complications. In situations where there is a low number of neutrophils, high lymphocyte levels could be brought about by lymphoma.


Low lymphocyte count – Causes

Decline in the level of lymphocytes is often attributed to infections, especially after a trauma or surgery. The condition can also result when human immunodeficiency virus infects and kills T-cells. When these cells are destroyed, the body lacks a mechanism to protect itself and opportunistic infections are now able to attack the body. The level of HIV spread in the cells is tracked by determining the amount of CD4 in T cells present in the blood system of a patient. As the condition progresses, HIV develops into AIDS (Acquired Immune Deficiency Syndrome). Counting lymphocytes in our blood can also help determine lymphocyte disorders and other viruses in our bodies.


Functions of lymphocytes

The overall function of various components of the immune system such as lymphocytes is to recognize foreign infectious agents or toxins and destroy them. For the immune system to eliminate threats in the body, the lymphocytes must differentiate between normal body cells and those that are infected. Every type of lymphocyte has the ability to perform this function. Some lymphocytes perform the general immune response functions while others are very specific to certain microorganisms and infected cells.

The major role of lymphocytes in our innate immune mechanism is delivering a quick response in case of viral and bacterial attacks. NK cells play a greater role than this since they also detect those cells that have microbial infections and those that are cancerous. NK cells act on these cells the same way they respond in cases of viral infections. They engulf them and completely destroy the infected cells. Despite the fact that the location and maturation process of NK cells is not clear to the scientists, billions of them are ever circulating in our blood system every time.

Our adaptive immune system is made of lymphocytes that are antigen-specific. The primary function of lymphocytes in this line is to recognize toxins and pathogens that the immune system has encountered before. During consequent encounters, it is these lymphocytes that respond immediately protecting the body from any kind of infection.


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