Lymphocytosis, Lymphopenia - Forms, Causes, Diagnosis, Therapy

Lymphocytosis and lymphopenia

Lymphocytes are cells of the adaptive immune system. They are formed in the bone marrow and thymus and then migrate to the so-called secondary organs of the lymphatic system - in the lymph nodes, spleen, tonsils and the lymphatic organs of our mucous membranes. Their diverse tasks include, above all, the defense against pathogens and abnormal cells such as cancer cells.

An adult's immune system is made up of around one kilogram of white blood cells (leukocytes). All leukocytes are derived from so-called hematopoietic pluripotent stem cells in the bone marrow, which develop different lines under the influence of different stimuli (growth and differentiation factors). Lymphocytes represent a significant part of the body's own acquired ("adaptive") immune defense.

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• What are the tasks of lymphocytes?
• What types of lymphocytosis are there?
• What types of lymphopenia are there?
• How is the diagnosis made?
• How is lymphocytosis and lymphopenia treated?
• Whom can I ask?
• How are the costs settled?

What are the tasks of lymphocytes?

Lymphocytes can be divided into different types according to their different tasks:

• B lymphocytes: They make up about 20 to 30 percent of the total lymphocytes and are responsible for the so-called humoral defense through the production of antibodies. They develop and mature exclusively in the bone marrow.
• T lymphocytes:They represent 70 to 80 percent of total lymphocytes and have functions as so-called T helper cells in the activation of B lymphocytes and as so-called cytotoxic T cells (formerly known as suppressor cells) in the direct killing of abnormal cells (e.g. tumor cells or virus cells). infected cells). There are also so-called regulatory T cells in small quantities. These prevent cytotoxic T cells or antibody reactions from being directed excessively against the body's own tissue and autoimmune diseases from developing. T-lymphocyte precursor cells migrate from the bone marrow into the thymus gland, where they undergo the final and decisive stages of maturation. Just the mature T-lymphocyteswhich do not react with the body's own structures and recognize the body's own identity cards (HLA molecules) well, eventually migrate into the body.
• Other types of lymphocytes: These include, for example, γ: δ T cells or natural killer T cells and natural killer (NK) cells.

If the number of lymphocytes is increased, it is called lymphocytosis, if it is decreased, it is known as lymphopenia.

What types of lymphocytosis are there?

The focus is on the distinction between reactive and clonal lymphocytoses. Reactive lymphocytoses arise as a mostly time-limited response to certain triggers, clonal lymphocytoses occur mainly in the context of lymphomas / leukemias.

Reactive lymphocytosis

The increased lymphocytes are polyclonal, ie there are cells with different T-cell receptors or B-cell receptors. There is a corresponding underlying disease (usually an infection). There is no suspicion of an underlying disease of the blood and blood-forming organs (such as leukemia or lymphoma) and so-called B symptoms (consisting of night sweats, fever and weight loss) or other changes in the blood count are rare. In most cases, lymphocyte counts return to normal within one to two months. Common causes of reactive lymphocytosis include:

Viral infections such as:

• Adenoviruses
• Coxsackie Viruses
• Cytomegaly virus
• Enteroviruses
• Epstein-Barr virus (glandular fever)
• hepatitis
• Herpes viruses
• HTLV-1 (Human T-lymphotropic virus 1)
• HIV
• Flu (influenza)
• measles
• mumps
• Poliovirus
• rubella

Bacterial infections such as:

• Bartonellosis
• Brucellosis
• Whooping cough (pertussis)
• Paratyphoid
• typhus
• syphilis
• tuberculosis

Infections with single-cell parasites such as:

• Toxoplasmosis
• Babesiosis (cattle malaria): is very relevant as more than half of all ticks in Austria are infected with Babesia.

Stress-induced lymphocytosis

This form occurs mainly in the context of hospital stays. Possible causes are mainly:

• cardiac emergencies (heart)
• severe injury
• severe forms of epilepsy (status epilepticus)

Post splenectomy lymphocytosis

This form can appear after removal of the spleen. It mainly affects people who have had their spleen removed after accidents with abdominal trauma or autoimmune diseases, erythrocyte malformations and problems with hemoglobin metabolism.

Clonal lymphocytosis

It is characterized by the presence of malignant diseases of the lymphatic system. The increased number of lymphocytes originate from a common mother cell. Monoclonality can be determined by examining the B-cell or T-cell receptor. In addition to this monoclonality, a continuous increase in the number of lymphocytes is usually observed. Clonal lymphocytoses are often associated with parallel associated cytopenias, ie reduced cell count (anemia, neutropenia, thrombopenia) and B symptoms.

What types of lymphopenia are there?

A distinction is made between primary (congenital) and - much more common - secondary (acquired) forms.

Primary lymphopenia

Primary lymphopenias are a specialty of paediatrics and are caused by inherited severe immune deficiencies (eg adenosine deaminase (ADA) deficiency, gamma chain deficiency, Bruton's disease). These are very rare diseases with severe, recurring infections and failure to thrive. Even small children are affected, and there is often a family predisposition. Those affected require intensive treatment, sometimes with bone marrow transplants or regular antibody infusions.

Secondary lymphopenia

Possible causes of development are either disorders of lymphocyte production or distribution or increased lymphocyte destruction. Common causes of secondary lymphopenia include:

• Infections (typically lymphopenia occurs acutely at the onset of the disease);
• Medication (e.g. glucocorticoids, alemtuzumab (anti-CD52) etc.);
• systemic diseases (autoimmune diseases from the systemic lupus erythematosus, lymphoma, sarcoid, kidney failure or heart failure);
• Malnutrition;
• high alcohol consumption.

How is the diagnosis made?

The lymphocyte reference values are subject to certain fluctuations and are relatively strongly age-dependent. Children and toddlers generally have higher values.

In the anamnesis, the existing symptoms are recorded, in particular aspects such as the so-called B symptoms (consisting of night sweats, fever and weight loss), weight gain, increase in height (in children) or bone pain and recent infectious diseases. A physical examination will determine whether the lymph nodes, spleen or liver are enlarged. In addition, laboratory tests such as blood count (assessment of red and white blood cells and platelets) and differential blood count (assessment of the subtypes of leukocytes) are carried out. This makes it possible to diagnose diseases of the lymphatic system and to get to the bottom of their forms and causes. For more information on lymphocytes and the reference values, see Laboratory Values Table - Lymphocytes.

Furthermore, different lymphocyte differentiation stages and subpopulations can be differentiated by means of flow cytometry. Such detailed analyzes can often simplify diagnosis considerably.

How is lymphocytosis and lymphopenia treated?

The therapy depends on the underlying disease or the respective trigger.

Whom can I ask?

The first diagnosis of lymphocytosis or lymphopenia is carried out at the following offices:

• General Practitioner,
• Specialist in paediatrics and adolescent medicine,
• Specialist in internal medicine.

Depending on the findings and the course, further examinations or therapies in special facilities may be necessary.

How are the costs settled?

All necessary and expedient steps for diagnosis and therapy are taken over by the health insurance carriers. Your doctor or the outpatient clinic will generally settle accounts directly with your health insurance provider. However, you may have to pay a deductible with certain health insurance providers (BVAEB, SVS, SVS, BVAEB).

However, you can also use a doctor of your choice (ie doctor without a health insurance contract) or a private outpatient clinic.

You can find more information under Costs and Deductibles and on the website of the social security agency.

When hospitalization is required

Hospitalization is required if serious infections occur. Here, the hospital costs are billed. The patient has to pay a daily contribution to the costs.

For more information, see What does a hospital stay cost?