(also spelled leukocytes), commonly known as white blood cells (WBCs) , are the mobile units of the body's defensive system. They are produced in the bone marrow and lymph tissue and are distributed throughout the blood and lymphatic systems. Unlike red blood cells, all leucocytes have nuclei, which is their primary distinguishing feature. Classification of Leucocytes
: They move from the bloodstream into tissues via the lymphatic vasculature using chemokine-directed "amoeboid movement". leucocyte
: Key players in the adaptive immune system, further divided into T cells (cell-mediated immunity) and B cells (antibody production). Function and Mechanism (also spelled leukocytes), commonly known as white blood
: The most numerous, acting as first responders to infection. (also spelled leukocytes)