lümfotsüüdid

Lümfotsüüdid, often shortened to lymphocytes, are a type of white blood cell that play a crucial role in the immune system. They are a fundamental component of adaptive immunity, meaning they help the body recognize and remember specific pathogens to mount a more effective defense upon subsequent exposure. Lymphocytes are produced in the bone marrow and mature in various lymphoid organs, including the thymus, spleen, and lymph nodes.

There are three main types of lymphocytes: B lymphocytes (B cells), T lymphocytes (T cells), and natural killer (NK) cells. B cells are responsible for producing antibodies, which are proteins that bind to specific antigens on pathogens, marking them for destruction. T cells are more diverse. Helper T cells assist B cells in antibody production and activate other immune cells. Cytotoxic T cells directly kill infected cells or cancer cells. NK cells, while often grouped with lymphocytes, are part of the innate immune system. They can recognize and kill stressed cells or cells infected with viruses without prior sensitization.

The primary function of lymphocytes is to identify and neutralize foreign invaders such as bacteria, viruses, and parasites, as well as abnormal cells like cancer cells. When a pathogen enters the body, lymphocytes are activated and proliferate, leading to an immune response. This response can involve the production of antibodies, direct cell killing, or the release of signaling molecules that coordinate the activity of other immune cells. The long-lived nature of some lymphocytes, particularly memory cells, allows for long-term immunity, providing protection against previously encountered threats.