Description: Lymphocyte subsets are specific groups of immune system cells that play crucial roles in the body’s immune response. Lymphocytes, a type of white blood cell, are mainly divided into three categories: T lymphocytes, B lymphocytes, and NK (natural killer) lymphocytes. Each of these subsets has distinct functions; for example, T lymphocytes are essential for the adaptive immune response, as they can recognize and attack infected or cancerous cells, while B lymphocytes are responsible for producing antibodies that neutralize pathogens. On the other hand, NK lymphocytes act as a first line of defense, attacking infected or tumor cells without prior activation. The diversity and specialization of these subsets allow the immune system to respond effectively to a wide variety of threats, from viruses and bacteria to malignant cells. The identification and characterization of these lymphocytes are essential for understanding the dynamics of the immune response and for the development of immunological therapies, such as vaccines and cancer treatments.