Subsection 1.5.4: Leukocytes (White Blood Cells)

Leukocytes (White Blood Cells)

• Function: Protect the body against infection, disease, and foreign invaders as part of the immune system.

Leukocytes (White Blood Cells)

• Appearance: Larger than erythrocytes and platelets. Have a nucleus and other organelles.

  • Classified into two main groups based on the presence or absence of visible cytoplasmic granules when stained: granulocytes and agranulocytes.

Leukocytes (White Blood Cells)

• Production: Produced in the red bone marrow from hematopoietic stem cells. Their production is stimulated by various colony-stimulating factors in response to infection or immune challenges.

Granulocytes

1. Function: First responders to infection. Ingest and destroy bacteria and cellular debris using enzymes and antimicrobial chemicals.

Granulocytes

1. Appearance: Granules stain a light violet-pink. The nucleus typically has three to five lobes. Immature forms called band cells have a U-shaped nucleus.

1. Eosinophils

1. Function: Attack parasitic worms, participate in allergic reactions, and help regulate inflammation by phagocytizing antigen-antibody complexes.

1. Eosinophils

1. Function: Attack parasitic worms, participate in allergic reactions, and help regulate inflammation by phagocytizing antigen-antibody complexes.

1. Eosinophils

1. Function: Attack parasitic worms, participate in allergic reactions, and help regulate inflammation by phagocytizing antigen-antibody complexes.

1. Eosinophils

1. Appearance: Granules stain bright red with eosin. The nucleus is usually bilobed.

1. Basophils

1. Function: 

   1. They release histamine and other inflammatory mediators when activated, which contributes to allergy symptoms like swelling, redness, and itching. 

   2. They release heparin to prevent clotting.

1. Basophils

1. Appearance: Granules stain dark violet with hematoxylin. The nucleus is bilobed but often obscured by granules.

Agranulocytes | Lymphocytes

1. Function: Central players in adaptive immunity.

2 different types of Lymphocytes

1. B lymphocytes: Produce antibodies that bind to antigens.

2. T lymphocytes: Enhance other immune responses, destroy cancer cells, and kill virus-infected cells.

1. Lymphocytes

1. Appearance: Large, dark-violet spherical nucleus with a thin rim of light blue-purple cytoplasm

1. Monocytes

1. Function: Mature into macrophages in tissues. Macrophages are active phagocytes that engulf bacteria, dead cells, and debris. They also present antigens to lymphocytes to activate the immune response.

1. Monocytes

1. Appearance: Largest WBC. Violet U-shaped or horseshoe-shaped nucleus with light blue or light purple cytoplasm.