Agranulocyte

Agranulocytes are a category of white blood cells that lack visible granules in their cytoplasm. The primary types of agranulocytes are monocytes and lymphocytes.

Blood cell lineage

Monocyte under a light microscope (40x) from a peripheral blood smear surrounded by red blood cells.

Definition

The term agranulocyte is derived from the prefix "a-" meaning "without" and the word "granule". Thus, agranulocytes are white blood cells without distinguishable granules in their cytoplasm when observed under a microscope. This differentiates them from granulocytes, which possess such granules.

Types

Agranulocytes can be primarily classified into two types:

• Monocytes: These cells are the largest type of white blood cell and play a vital role in fighting off certain types of infections, especially those caused by bacteria. They are also responsible for removing dead or damaged cells and helping with the immune response.

• Lymphocytes: Lymphocytes are critical for the body's immune response. They are responsible for producing antibodies and can directly attack cells or help control the immune response. They can be further sub-divided into T-cells and B-cells based on their functions.

Functions

Agranulocytes have a range of functions that contribute to the body's immune system:

• Response to Pathogens: Agranulocytes are essential for identifying and targeting various pathogens, including viruses, bacteria, and other harmful agents.
• Cellular Clean-up: Particularly monocytes can differentiate into macrophages which engulf and digest cellular debris and pathogens.
• Immunity Memory: Lymphocytes play a significant role in the adaptive immune system by remembering specific pathogens, ensuring faster and more efficient responses during future encounters.

Importance in Health and Disease

A balanced number of agranulocytes is essential for maintaining health and ensuring the effective functioning of the immune system. An abnormal count can indicate various conditions:

• An increase in lymphocytes might be seen in viral infections, certain types of leukemia, or lymphoma.
• A decrease in lymphocytes might indicate conditions like HIV/AIDS, severe malnutrition, or the effect of certain medications.

See Also

• White blood cell
• Granulocyte
• Immune system
• Lymphocyte
• Monocyte

Agranulocyte Resources
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