Lymphocytes - Kresser Institute Membership Site

Marker Name: Lymphocytes

REFERENCE RANGES FOR LYMPHOCYTES:

Laboratory reference range:
Relative 26–46%
Absolute: 0.7–3.1 x103/µL

Functional reference range:
Relative 25–40%
Absolute: N/A

DESCRIPTION:

Lymphocytes make up one of two major categories of white blood cells. The three main types of lymphocytes are B lymphocytes, T lymphocytes, and natural killer (NK) cells;¹ each type of lymphocyte plays several roles in the immune system. B lymphocytes, once they have been activated to form plasma cells, are the sole site of antibody synthesis in the body.² B cells also act as antigen-presenting cells, regulate dendritic cell function, participate in wound healing, produce cytokines, and participate in tumor immunity and transplant rejection.³

The primary tissues that produce B and T lymphocytes are the bone marrow and thymus gland, respectively. Various secondary lymphoid tissue such as lymph nodes, tonsils, spleen, and mucosal surfaces in the gastrointestinal tract and lungs also participate in lymphocyte production. B cells develop through several stages, including B progenitor cell (pre-pro-B cell), the pro-B cell, the pre-B cell, the naïve B cell, and the mature B cell.⁴ Activated B cells include antigen-activated B cells, plasma cells, and memory cells. B lymphocytes play a primary role in humoral immunity and a supporting role in cell-mediated immunity.^3,5

T lymphocytes, on the other hand, are the prime players in cell-mediated immunity.⁶ The main types of T lymphocytes are cytotoxic, helper, and memory T cells. Cytotoxic T cells seek out and destroy “infected” cells, which are cells bearing foreign antigen molecules on their cell membranes.⁴ Helper T cells, also called modulatory T cells, participate in inflammation, promote immune tolerance, and promote tumor immunity.⁷ Unfortunately, helper T cells may also participate in autoimmune disorders, allergy, hypersensitivity reactions, anaphylaxis, and perhaps tissue and organ rejection.⁸

Natural killer (NK) cells are part of the innate immune system. They can bind to and destroy certain tumor cells or virus-infected cells, presumably without prior antigen exposure. Natural killer cells can also regulate immune responses through interactions with dendritic cells, macrophages, endothelial cells, and T lymphocytes.⁹

When an absolute lymphocyte count (ALC) or lymphocyte percentage is reported on a complete blood count (CBC) with differential, it reflects the quantity of B lymphocytes, T lymphocytes, and natural killer cells.¹⁰ The absolute lymphocyte count can be calculated from a lymphocyte percentage and a total white blood cell count using the following equation:

Lymphocytes equation

An abnormally high number of lymphocytes in the blood is called lymphocytosis. There are several specific causes of lymphocytosis, but they can be broadly grouped as either reactive or clonal lymphocytosis. Reactive lymphocytosis may be caused by infections, especially viral infections, or a variety of noninfectious stressors such as drugs, stress, or surgery. Clonal lymphocytosis can be caused by monoclonal B cell lymphocytosis, which is premalignant, or a blood cancer, including chronic lymphocytic leukemia, non-Hodgkin lymphoma, or acute lymphoblastic leukemia.¹¹

An abnormally low lymphocyte count is called lymphocytopenia. Lymphocytopenia may occur in one or more of three general ways:¹² too few lymphocytes are produced, lymphocytes are destroyed faster than they can be replenished, or lymphocytes are sequestered in the spleen or within the lymph nodes. Lymphocytopenia may be genetic or acquired. The acquired causes of lymphocytopenia include infection, autoimmune disorder or its treatment, cancer or its treatment, and various stressors, such as nutritional deficiency or alcohol abuse.

A basic complete blood count (CBC) simply provides quantities of circulating cells in the bloodstream, including red blood cells, white blood cells, and platelets. To obtain a lymphocyte count, the CBC must be ordered with a differential, which tells the laboratory to provide a count of individual white blood cell types.¹⁰ A peripheral blood smear may be ordered as a follow-up test to investigate the morphology of lymphocytes.¹³ The presence of certain abnormal lymphocytes can help guide the precise diagnosis of lymphocyte abnormalities.

PATHOLOGICAL/CONVENTIONAL RANGE INDICATIONS:

High in:¹⁰

Infections
- Viral (e.g., EBV, CMV, HIV, mononucleosis)
- Bacterial (e.g., pertussis)
- Parasitic (e.g., babesiosis)
- Protozoal (e.g., toxoplasmosis)
- Rickettsial
Stressors (e.g., cigarette smoking, trauma, splenectomy)
Hyperthyroidism
Rheumatoid arthritis
Leukemias
Lymphomas
Serum sickness
Autoimmune lymphocytosis
Malignant thymoma
Monoclonal B cell lymphocytosis
Drugs
- Chemotherapeutics
- High-dose niacin supplementation

Low in:^10,14

Zinc deficiency
Protein malnutrition
Alcohol abuse
Infection
- Bacterial
- Viral
- Fungal
- Parasitic
Autoimmune disorders (e.g., lupus, rheumatoid arthritis)
Trauma
Genetic immunodeficiency disorders
Immunosuppressive therapy
Cancer (e.g., lymphoma)
Aplastic anemia
Cushing’s syndrome
Cancer treatment
- Chemotherapy
- Radiation therapy

FUNCTIONAL RANGE INDICATIONS:

High in:

Same as conventional indications
Viral infections

Low in:

Same as conventional indications
Bacterial infections

References: