Final answer:
Lymphocytes, which include B cells, T cells, and natural killer cells, are white blood cells that respond to threats like cancer cells, viruses, and bacteria by generating an immune response.
Step-by-step explanation:
Lymphocytes are a type of white blood cell (WBC) that play a crucial role in the immune response. They respond to a variety of threats including cancer cells, foreign proteins, and invading organisms. Specifically, lymphocytes are tasked with fighting infections caused by viruses and bacteria, and some are also known for attacking and killing cancer cells.
B cells, a category of lymphocytes, produce antibodies in response to pathogens. These antibodies are specialized proteins that bind to antigens found on the surfaces of bacteria, viruses, and other foreign microorganisms, marking them for destruction by phagocytes.
In addition to B cells, the body also has T cells and natural killer (NK) cells. NK cells are capable of recognizing cells that do not express 'self' proteins or that contain abnormal markers, including cancer cells and cells infected with a virus, providing generalized, nonspecific immunity. Meanwhile, T cells contribute to the cell-mediated immune response, which can target abnormal cells, such as cancer cells that may present tumor antigens.