What type of cells are B and T cells classified as?

B and T cells are classified as lymphocytes, which are a key component of the immune system. Lymphocytes are characterized by their large nucleus and small amount of cytoplasm, and they play critical roles in the body's adaptive immune response. B cells are responsible for producing antibodies that specifically target pathogens, while T cells are involved in directly killing infected host cells or helping activate other immune cells. This classification is crucial for understanding their functions, as lymphocytes are distinct from other types of blood cells, such as granulocytes, which are involved in the innate immune response, and erythrocytes, which are red blood cells responsible for oxygen transport. Monocytes, another type of white blood cell, differentiate into macrophages and dendritic cells, contributing to the immune system but serving different functions than lymphocytes.