Lymphocytes are a type of white blood cell that plays a crucial role in the immune system. They are produced in the bone marrow and can be found in various parts of the body, including the blood, lymph nodes, and spleen.
There are three main types of lymphocytes:
T cells: These cells are responsible for cell-mediated immunity, which involves the direct killing of infected or cancerous cells. T cells can be further divided into helper T cells, cytotoxic T cells, and regulatory T cells.
B cells: B cells are involved in humoral immunity, which is the production of antibodies to neutralize pathogens. When a B cell encounters a foreign substance (antigen), it can differentiate into plasma cells that secrete antibodies specific to that antigen.
Natural Killer (NK) cells: NK cells are a type of cytotoxic lymphocyte that plays a crucial role in the innate immune response. They are able to recognize and destroy infected or cancerous cells without prior sensitization.
Lymphocytes are vital for the body's defense against infections and diseases. They work together with other components of the immune system, such as macrophages and dendritic cells, to mount an effective immune response.
For example, when a person is infected with a virus, T cells recognize viral antigens presented by infected cells and initiate an immune response. B cells, on the other hand, produce antibodies that bind to the virus, preventing its entry into host cells and marking it for destruction by other immune cells.
References:
Janeway, C. A., Travers, P., Walport, M., & Shlomchik, M. (2001). Immunobiology: The Immune System in Health and Disease. 5th edition. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK10757/
Abbas, A. K., Lichtman, A. H., & Pillai, S. (2017). Basic Immunology: Functions and Disorders of the Immune System. 5th edition. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK343646/