Types of White Blood Cells Are leukocytes Protect against disease WBC hormones are interleukins and colony-stimulating factors which stimulate development There are five types of WBCs in two categories: Granulocytes Neutrophils Eosinophils Basophils Agranulocytes Lymphocytes Monocytes

Neutrophils Light purple granules in acid-base stain Lobed nucleus Other names Segs Polymorphonuclear leukocyte Bands (young neutrophils) First to arrive at infections Phagocytic 54% - 62% of leukocytes Elevated in bacterial infections Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke

Eosinophils Deep red granules in acid stain Bi-lobed nucleus Moderate allergic reactions Defend against parasitic worm infestations 1% - 3% of leukocytes Elevated in parasitic worm infestations and allergic reactions Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke

Basophils Deep blue granules in basic stain Release histamine Release heparin Less than 1% of leukocytes Similar to eosinophils in size and shape of nuclei Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke

© R. Kessel/Visuals Unlimited Monocytes Largest of all blood cells Spherical, kidney-shaped, oval or lobed nuclei Leave bloodstream to become macrophages 3% - 9% of leukocytes Phagocytize bacteria, dead cells, and other debris Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © R. Kessel/Visuals Unlimited

Lymphocytes Slightly larger than RBC Large spherical nucleus surrounded by thin rim of cytoplasm T cells and B cells Both important in immunity B cells produce antibodies 25% - 33% of leukocytes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Ed Reschke

Functions of White Blood Cells WBCs protect against infection These leukocytes can squeeze between the cells of a capillary wall and enter the tissue space outside the blood vessel (called diapedesis) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Connective tissue Blood capillary Leukocyte