Lymphocytes are a major type of white blood cell alongside neutrophils, monocytes, eosinophils and basophils. Lymphocytes make up approximately a quarter of the total white blood cell count and help to protect the body against infection.
Lymphocytes have an important role in the immune system. What they do depends on which type of lymphocyte they are. There are two main types of lymphocyte: B cells and T cells. B cells produce antibodies – Y-shaped proteins - to attack invading pathogens such as bacteria, viruses and toxins. T cells, on the other hand, destroy the body’s cells which have become cancerous or have been invaded and taken over by viruses.
As lymphocytes are a marker for infection or inflammation you may feel weak, tired, have a fever, bruise easily, lose weight, have pain in your joints, have swollen lymph nodes or keep picking up infections such as coughs and colds. This is because your immune system is already compromised and trying to fight an infection elsewhere in your body.
An infection can also reduce your energy levels and make your mood low. You may feel generally unwell or like you can’t carry out your usual daily activities. Infections often occur during the colder, winter months which may also influence your mood.
A low lymphocyte count or lymphocytopenia can be caused by immunodeficiency diseases. The condition may not present with any symptoms and its duration can depend on its severity and cause.
You may not be able to directly influence your lymphocyte count but with a good lifestyle, you can improve the efficiency of your immune system.
Smoking can also damage your immune system and its response. However, some of the damage is reversible if you stop smoking.
Nutrition is an important factor in our health and immune status. If we are deficient in some nutrients, then this can make our immune system weak. Micronutrients including zinc, selenium, iron, copper, vitamins A, C and E, B6 and folic acid all have important influences on our immune responses. Therefore, it is essential to maintain a healthy and balanced diet incorporating all these micronutrients.
Hydration is an important factor in the status of the immune system. Our saliva contains an antibody, IgA, and is our body’s first line of defence against infection. Therefore, we need an adequate supply of fluid to ensure sufficient saliva production.
Exercise is key to a healthy lifestyle. However, intense exercise can also induce immunodepression during recovery. Therefore, it is essential that you take rest periods between bouts of intense exercise to prevent illness.
 PubMed Health. (2018). Lymphocytes. Available at: https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022042/
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 Chandra, R, K. (1997). Nutrition and the Immune System: An Introduction. American Journal of Clinical Nutrition: 66, pp 460S-463S.
 Peake, J, M., Neubauer, O., Walsh, N, P and Simpson, R, J. (2016). Recovery of the Immune System After Exercise. Journal of Applied Physiology: 122, pp 1077-187.