Overview

Although blood appears to be a single component and red in colour, it consists of different types of cells. These cells perform different functions which help the individual to live a healthy life and to protect against different infections. The blood cells consist of red blood cells (RBCs), white blood cells (WBCs) and platelets. WBCs help in the proper functioning of the immune system. Some of the WBCs include lymphocytes. Lymphocytes consist of T-lymphocytes and B-lymphocytes. B-lymphocytes make antibodies against infections. T-lymphocytes have an exceptional role in the destruction of infected cells. Lymphopenia or lymphocytopenia is a condition where there is a reduction in the count of lymphocytes in the blood. A considerable reduction in lymphocytes affects the body’s immune mechanism. Malnutrition and depletion of nutrients and proteins can result in lymphopenia and thereby affect the immune system, and can cause infection. Malnutrition is a common problem arising due to poor dietary intake, malabsorption, side effects of any medical condition and an elevated rate of nutrient loss. Immune function is affected due to malabsorption, resulting in infections. The wound healing gets delayed after surgery in malnourished people. The immune system has a major role in maintaining overall health and well-being.

Malnutrition and immune function 

The immune system is a complex network of cells, tissues and organs that work harmoniously to fight against infections caused by microorganisms.¹ The immune system is of two types, which include the innate immune system and the adaptive immune system. The innate system provides immediate and nonspecific defence mechanisms, like the skin and white blood cells, which can rapidly respond against pathogens. The adaptive immune system is specific, and it allows a targeted and efficient response to a particular pathogen which attacked previously.² Children generally have a resilient immune system. Children respond quickly to an infection. The immune system is an astonishing defence mechanism that is influenced by dietary factors. Malnutrition debilitates the immune system, diminishing its ability to defend the body against infections. Proteins are essential for the proper functioning of the immune system and the repair of the muscles and tissues. Proteins have an influence on cytokine production, which regulates immune responses. Protein energy malnutrition (PEM) causes immunodeficiency, which depletes the cell-mediated and humoral immunity. 

Pathophysiology of lymphopenia in malnutrition and protein-energy wasting

Malnutrition affects the immune system by altering gene expression through epigenetic modification. Malnutrition compromises the T-cell function. Protein deficiency causes bone marrow suppression, which causes a reduction in the synthesis of lymphoid precursors. Deficiency of micronutrients like zinc, iron, vitamin B12, copper and folate reduces lymphocyte proliferation. Elevated levels of cortisol, the chronic stress hormone, in malnutrition can deteriorate lymphocytes. Protein deficiency can lead to the depletion of lymphoid tissue. It also reduces the production of immunoglobulins and cytokines, which are needed for the proper functioning of lymphocytes.

Clinical significance of lymphopenia in malnutrition and protein-energy wasting

Lymphopenia reflects impaired cell-mediated immunity. A defective immune mechanism causes infections. Malnourished people with lymphopenia are highly susceptible to pneumonia, tuberculosis, gastrointestinal problems, skin infections and sepsis. Lymphopenia can result in poor wound healing. It can cause higher morbidity and mortality in people with chronic diseases like cancer, heart problems and kidney failure. Persistent lymphopenia may be associated with inadequate nutritional intervention.

Diagnosis and assessment

The diagnosis of lymphopenia depends upon an analysis of family history, which will point towards genetic disorders, physical examination, and other test results. Screening of a newborn will identify early stages of genetic diseases that can lead to lymphopenia. 

Medical history and physical examination

The physician will examine for fever or other symptoms, such as enlarged lymph nodes and spleen. They may also enquire about your medical conditions to observe any autoimmune diseases, any history of blood transfusions or other infections. The physician will ask about the dietary habits and the socioeconomic status to consider any malnutrition or protein insufficiency conditions.

Diagnostic tests

Complete blood count - This test analyses the count of different cells in the blood, which includes red blood cells, white blood cells and platelets. A low count of lymphocytes indicates lymphopenia. A normal lymphocyte count in adults ranges between 1000 to 4800 per microliter of blood.³ If the count is less than 1500, it can be interpreted as lymphopenia. Lymphocyte count in children depends on the child's age, as younger children can have higher counts of lymphocytes.³

Flow cytometry

This test examines the level of different types of lymphocytes, which include B-cells and T-cells (Helper T-cells and cytotoxic T-cells). This helps to provide an understanding of the cause of lymphopenia.

Immunoglobulin level test

When a pathogen or virus attacks the body, the B-cell receptors, which are present on the surface of B-cells, get discarded and turn into antibodies that neutralise the pathogens. These antibodies belong to immunoglobulins. Their counts in the blood can give an insight into the extent of B-cell destruction due to the underlying cause.⁴

Tests for bone marrow and lymph nodes can be advised by the physician.

Management and treatment of lymphopenia

The treatment of lymphopenia depends on its cause. Mild lymphopenia, which is caused due to malnutrition or protein deficiency, can be cured by altering the dietary habits and following a diet with balanced nutrition. Certain dietary components, such as antioxidants and anti-inflammatory components, such as fruits, vegetables and probiotics, which are abundantly found in yoghurt, positively influence immune function.⁵ A low lymphocyte count can cause repeated bacterial and viral infections. These infections should be treated promptly to avoid complications. Immunoglobulins improve the immune response and prevent infections. If the cause of lymphopenia is an autoimmune disorder like HIV/AIDS or lupus, among many others, treatment of the condition helps improve the lymphocyte count. Research is ongoing to develop medicines to improve the lymphocyte count. Potential new treatments, including bone marrow and stem cell transplants, are being developed to cure lymphopenia and increase the lymphocyte count.

FAQs

What are the risk factors of lymphopenia in malnutrition and protein-energy wasting?

Malnutrition weakens the immune system. The main risk factors include poverty, limited food access, poor food habits, health conditions and a lack of education.⁶

Which population is at risk of lymphopenia?

Individuals with chronic diseases like kidney disease, heart problems, autoimmune conditions like HIV/AIDS, lupus, arthritis and other infections like tuberculosis are at high risk of lymphopenia. People who are inaccessible to balanced dietary habits and protein-rich food are also at risk of developing lymphopenia.

Should I consult a doctor?

If you have persistent or repeated infections, fatigue, gut-related problems, skin infections or any other symptoms of low immunity, you should consult a physician.

Summary

Lymphopenia is a condition where there is a reduction in the count of lymphocytes in the blood. A considerable reduction of lymphocytes can affect the body’s immune system. Malnutrition and protein insufficiency a major factors causing lymphopenia. Proper nutrition is essential for a powerful immune system. Protein energy malnutrition causes immunodeficiency. Protein deficiency affects antibody production, which results in a weakened response against pathogens.⁷ A defective immune mechanism causes infections. Malnourished people with lymphopenia are highly susceptible to infections. The diagnosis of lymphopenia is done by physical examination, medical history and other diagnostic tests, which include total blood count, flow cytometry, immunoglobulin tests and examination of bone marrow and lymph nodes. The treatment of lymphopenia depends on the causal factor. Lymphopenia due to malnutrition can be managed by providing a proper, balanced diet. Altering dietary habits can bring considerable improvement. In case of infections, it should be treated promptly to avoid complications. Lymphopenia caused due to immunocompromised conditions like HIV/AIDS can be managed by treating the condition. A sensible approach to nutrition, ensuring a balanced and nutrient-rich diet, is instrumental in promoting optimal immune health and overall well-being.