Lymphocytes are a type of white blood cell that play a significant role in the immune system of the body. They are primarily involved in the identification and elimination of foreign pathogens, like bacteria, viruses, and other harmful agents. There are three main types of lymphocytes:
- B cells (B lymphocytes): These cells are responsible for antibody production. Antibodies are proteins that specifically target and bind to foreign substances, known as antigens. B cells can also present antigens to T cells and are critical in the formation of immunological memory.
- T cells (T lymphocytes): T cells come in several types with different functions:
- Helper T cells (Th cells): These cells help activate B cells to secrete antibodies and macrophages to destroy ingested microbes. They also help activate cytotoxic T cells to kill infected target cells.
- Cytotoxic T cells (Tc cells): These cells are directly responsible for killing infected cells, cancer cells, and cells damaged in other ways.
- Regulatory T cells (Treg cells): These cells are crucial for maintaining immunological tolerance. They prevent the immune system from attacking the body's own cells and regulate the intensity and duration of immune responses.
- Natural Killer (NK) cells: NK cells play a role in the innate immune system. They can kill virus-infected cells and tumor cells and can recognize stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction.
Each type of lymphocyte has a unique function in the immune response. B cells are primarily involved in humoral immunity (mediated by antibodies), while T cells are key players in cell-mediated immunity, which does not involve antibodies. NK cells provide a rapid response to virally infected cells and respond to tumor formation. Collectively, these cells ensure a comprehensive and adaptive immune response to pathogens and abnormal cell conditions.