Kimberly T. answered • 06/09/19
ANATOMY & FORENSIC SCIENCES
Structurally, there are 2 groups: Granular and Agranular. As the prefix A- denotes, agranular WBC's have no visible granules, while the granular ones do. There are 3 types of Granular leukocytes: Neutrophils, Eosinophils, and Basophils. There are 2 types of Agranular leukocytes: Monocytes and Lymphocytes. The nucleus in granulocytes is segmented or lobed, compared to the nucleus in agranulocytes which is typically round or oval in lymphocytes and more of an amoebic appearance in monocytes. Size wise, a monocyte is usually larger than all others while the lymphocytes are the smallest. All are usually larger than a normal red blood cell.
Functionally, all are major components of the immune system. Basophils, neutrophils, eosinophils and monocytes are involved in INNATE immunity, while lymphocytes are the major player in ADAPTIVE immunity. Specifically, basophils initiate inflammation and release histamine and heparin. Eosinophils perpetuate the inflammatory response and allergic reactions. Neutrophils are the first responders and are major phagocytes involved in bacterial infections. Monocytes mature into macrophages and clean up dead cellular material and are found in the liver, spleen, lymph nodes, lungs and intestines. Lymphocytes direct the immune system. The majority of them are T cells which provide the immune system with "memory". The other 25% are B cells which produce antibodies.
