4.2 WBC Types

Neutrophil

 most numerous (50-70%), large, nuclei have 3-6 lobes, cytoplasm contains fine granules (contain hydrolytic enzymes, antimicrobial proteins), first line of defense against bacteria/inflammation, phagocytes, short life span (6hr - few days), pale red and blue cytoplasmic granules

Eosinophils

bilobed nucleus, red cytoplasmic granules (contain digestive enzymes), relatively rare (2-4%), large size, defense cell against parasitic worms, complex role in allergy and asthma, lifespan 5 days 

Basophil

 bilobed nucleus, purplish-black cytoplasmic granules (contain histamine and heparin), roles in allergy, lifespan few hrs to days, large size, very rare (0.5-1%)

Lymphocyte

common (25-45%), small cytoplasm, large spherical nucleus, thin rim of pale blue cytoplasm, role in fighting infection, lifespan few hrs to years (vaccination targets memory response in these), includes T (fight infected/cancerous cell) and B lymphocytes (release antibodies to attack free bacteria)

Monocyte

large kidney-shaped nucleus, abundant pale blue cytoplasm, largest leukocyte, moderately common (3-8%), when in blood stream = monocytes, when in tissue = macrophages, highly phagocytic and release cytokines (bacteria and viruses, dying RBC and neutrophils, active lymphocytes), lifespan months +