Lymphocyte - Wikipedia tes but MeSH D008214 TH H2.00.04.1.02002 FMA 62863 Anatomical terms of microanatomy [edit on Wikidata] A lymphocyte is one of the subtypes of a white blood cell in a vertebrate's immune system. <span>Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic adaptive immunity), and B cells (for humoral, antibody-driven adaptive immunity). They are the main type of cell found in lymph, which prompted the name "lymphocyte". Contents 1 Types 1.1 T cells and B cells 1.2 Natural killer cells 2 Development 3 Characteristics 4 Lymphocytes and disease 4.1 High 4.2 Low 4.3 Tumor-infiltrating lymphocytes 5 Blood c