Unit 4 - Types of Leukocytes

Blood, Blood Cells, Clotting Cascade, Blood Vessels, Blood Pressure,

Myeloid Stem Cell

Type of blood stem cell that differentiates into red blood cells, platelets, and myeloblasts which become granulocytes (eosinophils, basophils, and neutrophils)

Lymphoid Stem Cell

Type of blood stem cell that differentiates into lymphoblasts which become B lymphocytes, T lymphocytes, and natural killer cells

Neutrophil

60-70%, innate, granulocytes. First responders; phagocytize bacteria and fungi and promote inflammation. Release toxic substances stored in their granules to kill pathogens

Eosinophil

1-3%, innate, granulocytes. Kill parasitic worms by releasing toxic substances stored in their granules. Regulate inflammation by deactivating histamine. 

Basophil

<1%, innate, granulocyte. Help fight infections and allergies → release chemicals like histamine and cytokines → help to regulate the inflammatory response. Release heparin to prevent blood clots.

Macrophage

1-6%, innate, monocyte. “garbage collectors”, phagocytize pathogens, dead cells, and other debris. Release cytokines to recruit other immune cells at site of damage/infection.

Dendritic Cell

1-6%, innate and adaptive, monocyte. Forms bridge between innate and adaptive, presenting antigens to lymphocytes. Patrol tissues for pathogens or abnormal cells like cancer, migrate to lymph nodes to activate specific lymphocytes. Primary APC

B Cell

Part of 20-30%, adaptive, lymphocyte. Produce antibodies to fight infections and neutralize pathogens. Act as APC to activate other immune cells (T cells). Form memory cells for a faster response. Do not require antigen presentation.

T Cells (Antigen presentation)

Part of 20-30%, adaptive, lymphocyte. Destroy infected or cancerous cells by releasing cytotoxins, direct other immune cells through cytokines signals, regulate immune response to prevent autoimmune disease. Form memory cells for faster response.

Natural Killer (NK) Cells

Part of 20-30%, innate, lymphocyte. Release enzymes and toxins to kill cancer cells and virus-infected cells. Kill target cells immediately, without needing to be pre-activated by other cells