What are the functions of lymphocytes?

Lymphocytes are white blood cells that play a crucial role in helping the body’s immune system fight foreign pathogens, infection, and cancer. There are three types of lymphocytes – T lymphocytes, B lymphocytes, and natural killer cells. 

• T lymphocytes (T cells): T lymphocytes provide cell-mediated immunity. They control the body’s immune response by migrating to target tissues in case of an infection and directly attacking and killing the infected and tumor cells. They have a local action. 
• B lymphocytes (B cells): B lymphocytes provide humoral immunity. When stimulated by an antigen, they multiply and produce specific antibodies. These antibodies circulate in the blood as a soluble protein and provide immunity over a long distance.  
• Natural killer cells (NK cells): Natural killer cells are effector cells of the innate immune system. They play a pivotal role in limiting the spread and action of several types of tumors and microbial infections, thereby limiting subsequent tissue damage.