Lymphocytes (LYM, Lymphs, ly)
A lymphocyte is one of the subtypes of leukocytes (white blood cells) and the key element of the immune system. Lymphocytes are produced in the bone marrow, lymph nodes and spleen, and are found in blood and lymph. Lymphocytes are able to recognize non-sharedantigens (proteins) which they have encountered before. Due to this ability, people are immune to various infectious diseases. This means when some antigen enters the body, our lymphocytes already know how to fight it.
The two major types of lymphocytes are T cells – lymphocytes involved in cell-mediated immunity, and B cells– responsible for antibody production, i. e. humoral immunity.
An increase in the number of lymphocytes is called lymphocytosis. Lymphocytosis is associated with many childhood diseases, especially viral ones. Lymphocytosis may occur during the recovery period after infectious diseases and intoxications. It may last for 1 month after recovery or even longer.
A decrease in the number of lymphocytes is called lymphopenia. Lymphopenia, both relative and absolute, may occur at the beginning of infectious diseases.