Page 128 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

• Highly efficient at phagocytizing and destroying foreign material, particularly

bacteria, and damaged cells

• They normally account for over 50% of leukocytes circulating, and their

numbers increase during most acute bacterial infections.

• There are generally few in tissues except during inflammation.

• They contain two kinds of granules, the contents of which are involved in the

antimicrobial properties of these cells:

A) The primary or azurophilic granules
- are abundant in young newly formed PMNs, contain:

o Cationic proteins and defensins that can kill bacteria.

o Proteolytic enzymes like elastase and cathepsin G to breakdown proteins.

o Lysozyme to break down bacterial cell walls.

B) The second type of granule
- found in More mature PMNs is the secondary or specific granule. contain:
o Lysozyme, NADPH oxidase components, which are involved in the

generation of toxic oxygen products.

o Lactoferrin, an iron chelating protein.

2. Basophils

• Blood cells are involved in allergic reactions and

inflammation.

• Their granules, which stain dark purplish-blue with
the basic dye hematoxylene.

• Activation leads to degranulation; their granules contain histamine and other

chemicals that increase capillary permeability during inflammation.

General Microbiology & Immunology (PM 401) theoretical handbook Page 117