LYM: What It Is, Its Function, and Implications of High and Low Levels

Lymphocytes (LYM) are produced in the bone marrow and found in the blood and lymphatic tissues. They play a crucial role in defending the body against foreign substances such as bacteria, viruses, and cancer cells that impede the function of the immune system.

What is LYM?

Some of the lymphocyte cells continuously produced by the bone marrow enter the bloodstream, while most pass through the lymphatic system. The lymphatic system consists of tissues and organs, such as the spleen, tonsils, and lymph nodes, that protect the body from infections. Approximately one-quarter of newly produced lymphocytes remain in the bone marrow and develop into B cells. The remaining three-quarters go to the thymus and become T cells.

The primary function of B and T cells is to fight infections, and there are different types of these cells. They are as follows:

• Effector cells activated by antigens to combat an active infection.
• Memory cells that recognize past infections in the body and can quickly mobilize in the event of reinfection with the same antigen.

What Does LYM Do?

Lymphocytes perform various functions depending on their types. The types and functions of lymphocytes are as follows:

B Cells

• Memory B Cells
  Memory B cells are responsible for producing a rapid antibody response when the body encounters a foreign substance. They remain in the body for years, remembering previously encountered antigens, and help the immune system respond more quickly to future attacks.
• Regulatory B Cells
  Regulatory B cells, or Bregs, make up about 0.5% of all B cells in a healthy individual. Despite their small numbers, they play vital roles. Regulatory B cells exhibit protective anti-inflammatory effects in the body and help stop inflammation. They also interact with other immune cells to promote the production of regulatory T cells.

T Cells

• Cytotoxic T Cells
  Cytotoxic or killer T cells can detect the presence of infections or cancerous cells in the body by scanning the surfaces of body cells. When they identify a dangerous situation, they destroy these cells.
• Helper T Cells
  Helper T cells, as the name suggests, enable other cells in the immune system to initiate an immune response against all types of foreign substances entering the body. There are different types of helper T cells, and some are more effective against certain types of pathogens than others. For example, a Th1 cell has a greater impact on microbes causing infections within cells, while a Th2 cell is more effective in fighting infections caused by certain bacteria and parasites outside of cells.
• Regulatory T Cells
  Regulatory T cells control other cells in the immune system and exert dominance over them. They are known to have both beneficial and harmful effects. While maintaining their activity against pathogens, they prevent autoimmune diseases and protect against inflammatory diseases. However, they can also hinder the immune system's effectiveness against certain antigens and tumors.
• Memory T Cells
  Memory T cells protect the body from previously encountered antigens. They continue to live for a long time after an infection has resolved, allowing the immune system to remember past infections. If the same foreign substance enters the body a second time, memory T cells recognize it and quickly proliferate to assist the body in fighting it more effectively.
• Natural Killer T Cells
  Natural killer T cells are a complex group of cells that possess features of both T cells and natural killer cells. They can also regulate the immune response by influencing other immune cells while generating an immune response in the body.

What is Low LYM?

Lymphocyte counts below the normal range are referred to as low LYM and may be temporary. This can occur if you have experienced a cold or any other infection. Additionally, intense exercise, excessive stress, or inadequate nutrition can also be contributing factors.

A low LYM level may indicate a condition known as lymphocytopenia or lymphopenia. It can also be a side effect of medications or other medical treatments. Furthermore, lymphocytopenia can be hereditary or manifest alongside certain diseases, including:

• Rare genetic disorders such as ataxia-telangiectasia
• Neurological diseases like multiple sclerosis (MS)
• Autoimmune diseases
• Infectious diseases (AIDS)

The lymphocyte counts signaling lymphocytopenia can vary between adults and children. Typically, for adults, it is less than 1,000 lymphocytes per µL of blood, while for children, it is less than 3,000 lymphocytes per µL of blood.

What is High LYM?

Lymphocyte counts above the normal range are referred to as high LYM. This condition is usually harmless and temporary, resulting from the body's normal response to an infection or inflammatory condition. However, high levels of lymphocytes can sometimes indicate a more serious condition known as lymphocytosis.

Lymphocytosis is often associated with chronic infections, certain blood cancers, and inflammatory bowel diseases.

In adults, lymphocytosis is generally indicated by a lymphocyte count greater than 3,000 lymphocytes per µL of blood. In children, lymphocytosis corresponds to approximately 9,000 lymphocytes per µL of blood, although these values may vary with age.

What Do the Results Mean?

A low lymphocyte count can be interpreted as a cold. A screening of B and T cells can provide information about the amounts of T and B cells in the blood, indicating normal or abnormal cell counts. If a second possible disease is present, it draws attention to that condition. In this case, your doctor will likely request additional tests to confirm the diagnosis.

Elevated T cell counts may indicate the following conditions:

• Sexually transmitted diseases such as syphilis
• Viral infections like infectious mononucleosis
• Infections caused by parasites, such as toxoplasmosis
• Diseases affecting the lungs and other organs
• Cancers related to white blood cells
• Blood cancers arising in the bone marrow

Elevated B cell counts above the normal range may indicate:

• Chronic lymphocytic leukemia
• Multiple myeloma
• A familial disease known as DiGeorge syndrome
• A type of cancer called Waldenström macroglobulinemia

Decreased T cell counts below the normal range may indicate:

• Congenital diseases
• T cell deficiency diseases (HIV or those that may progress to HTLV-1)

Decreased B cell counts below the normal range may indicate:

• Acute lymphoblastic leukemia
• HIV or another disease that weakens the immune system

Unusually high or low LYM counts may show no symptoms or may not lead to serious problems on their own. They can also be a normal response of the body to an infection, inflammatory condition, or other unusual circumstances, and they may return to normal levels afterward.

If lymphocyte counts remain high or low for a prolonged period, they may be indicative of a disease, leading to a diagnosis of lymphocytopenia or lymphocytosis. The treatment of diseases caused by abnormal lymphocyte levels depends on the underlying reason and the severity of the condition. Sometimes, treatment may not even be necessary for mildly abnormal levels.

Chronic low lymphocyte counts can make you vulnerable to infections, increasing your risk of contagious diseases. To boost your immune system, you should prioritize hand hygiene and wash your hands regularly and thoroughly. Additionally, you should avoid contact with individuals who have colds or other infectious diseases. In most cases, very high lymphocyte counts tend to resolve within a few weeks. If lymphocytosis persists, specific blood tests can help clarify the situation. If the cause is not clear, your doctor may refer you to a hematologist specializing in blood disorders. It's essential to maintain normal levels of lymphocytes, your immune system's strong defenders. Consult your doctor about your abnormal lymphocyte counts.