Lymphopenia is a blood disorder that causes a decrease in certain white blood cells, called B and T lymphocytes, and affects the effectiveness of the immune system. It is defined by a total lymphocyte level of less than 1 per mm500 in adults and 3 mm4 in children under eight months of age. Sometimes hereditary, lymphopenia is most often secondary to other causes, the most common of which are malnutrition and AIDS.

Definition of lymphopenia

Lymphopenia is a blood disorder that manifests itself in a decrease in certain white blood cells, called B and T lymphocytes. It is defined by a total lymphocyte count of less than 1 per mm500 in adults and 3 mm4 in adults. child under eight months.

Lymphocytes represent 20 to 40% of the total number of white blood cells in the blood and play different roles in the immune system such as protection against bacteria, viruses, fungi and parasites.

Types of lymphopenia

Lymphopenia can be:

• Acquired: it is then secondary to many diseases;
• Hereditary.

Causes of lymphopenia

The causes of lymphopenia are numerous and can be classified according to their consequences on lymphocytes:

• Insufficient lymphocyte production: primary (including Wiskott-Aldrich syndrome) or secondary immune deficits, due to zinc deficiency, protein-calorie malnutrition or alcoholism;
• Excess catabolism – all of the chemical reactions that break down molecules – of lymphocytes linked to radiotherapy, chemotherapy, immunosuppressive treatments, the human immunodeficiency virus (HIV) or AIDS, systemic lupus erythematosus (autoimmune disease) );
• A change in the distribution of lymphocytes: hypersplenism (excessive activity of the spleen), certain viral infections (hepatitis, influenza, tuberculosis, typhoid fever, sepsis, etc.), septic shock, extensive burns, granulomatosis (diseases including inflammatory tumors, breast tissue.) and corticosteroid therapy;

Other causes are listed but their mechanism is still poorly understood:

• Renal failure;
• Lymphoma (cancer of the lymphatic system that develops at the expense of lymphocytes);
• The solid tumor (more or less large size due to an excessive multiplication of cells, cancerous or not);
• Rheumatoid arthritis;
• Idiopathic lymphopenia, characterized by the decrease in the number of circulating CD4 T lymphocytes …

Diagnosis of lymphopenia

The diagnosis of lymphopenia is made by a hematologist.

Lymphopenia is assessed first by measuring the level of B and T lymphocytes in the blood via the complete blood count. It is confirmed when this rate is less than 1 per mm500 in adults and 3 mm4 in children under eight months of age.

Other tests are then done to find the cause of the lymphopenia:

• Complete blood count or blood count (CBC);
• Blood strength and clearance – the ratio between the rate at which creatinine is eliminated by the kidneys (through urine) and its concentration in the blood – of creatine;
• C-reactive protein assay (PCR) which serves as a biological marker of inflammatory reactions;
• Electrophoresis – allows the separation of proteins from the blood, under the influence of an electric field – for the determination of albumin and gamma globulins (blood products rich in antibodies);
• Assay of anti-nuclear antibodies and anti-native DNA antibodies;
• Determination of lacticodehydrogenases (LDH), enzymes synthesized by our cells and transporters of hydrogen;
• Determination of angiotensin converting enzyme, a peptide involved in the maintenance of blood volume and blood pressure;
• Blood (calcemia) and urinary (calciuria) determination of calcium;
• Immunophenotyping of T and B lymphocytes;
• Serologies of HIV and HTLV (Human T-Lymphotropic Virus) viruses;
• Chest x-ray.

People affected by lymphopenia

When it is not hereditary, lymphopenia is secondary to a disease: everyone can therefore potentially be affected. But it particularly affects people suffering from malnutrition or AIDS.

Factors favoring lymphopenia

The number of lymphocytes may temporarily decrease in the following situations:

• Malnutrition ;
• Certain viral infections, such as the flu or hepatitis;
• The young ;
• Moments of significant physical stress;
• The use of corticosteroids;
• Chemotherapy and / or radiotherapy when treating cancer;
• Belonging to certain ethnic groups, such as the Ethiopians.

No symptoms

Lymphopenia usually does not have any symptoms on its own. On the other hand, the signs of the associated disorder can be numerous.

Recurrent infections

Lymphopenia induces recurrent infections in the patient or those caused by unusual microorganisms.

Skin abnormalities

Alopecia (accelerated hair loss or hair loss), eczema, pyoderma (purulent skin disease), telangiectasia (dilation of small blood vessels near the surface of the skin, mucous membranes or the white of the eye) are also skin abnormalities that may suggest the presence of lymphopenia.

Other symptoms

• Pallor;
• Petechiae, small red to purplish skin spots;
• Jaundice or jaundice;
• Oral ulcers;
• Enlarged lymph nodes and spleen – may suggest HIV infection;
• Tonsils or small lymph nodes – suggests an inherited disorder of the immune system;
• Painful swollen joints and rash – suggests rheumatoid arthritis or systemic lupus erythematosus.

In the event of a moderate abnormality –the lymphocyte count is greater than 1 per mm200– and without associated clinical signs, lymphopenia should be monitored but does not necessarily require immediate treatment.

Treatment of lymphopenia then varies depending on the cause detected:

• When it is due to an infection, a specific treatment (antibiotic, antifungal, antiviral or antiparasitic) targets the responsible microorganism;
• When it is the result of malnutrition, it is a question of correcting deficiencies;
• If induced by a drug, lymphopenia usually resolves within a few days after stopping the drug;
• If it is due to AIDS, a combination of drugs comprising at least three antivirals from different classes (triple therapy) can cause an increase in the number of T lymphocytes and prolong survival;
• Hematopoietic stem cell transplantation may be considered in people with hereditary immune deficiency.

To prevent infections associated with lymphopenia, gamma globulins may be prescribed intravenously to patients with B-cell deficiency.