Immune system refers to the collection of mechanisms involving cells, tissues and organs that protects organisms against disease by identifying and killing pathogens and tumour cells. Both these Neutrophils and Macrophages are phagocytes primarily involved in non-specific defence mechanism. This defence strategy is same for most type of infections or pathogens, hence called as non-specific defence mechanism. It protects body from primary infection by blocking pathogen entry or destroying pathogens that has entered, by different means other than antibodies. Phagocytes are vital in the host defense against microbial infection.
 Macrophages vs Neutrophils
Macrophages are antigen presenting phagocytes with antigen presenting capacity to T cells or can act as antigen presenting cells (APC)
Neutrophils are phagocytes without antigen presenting capacity
MHC Class II receptor is present as Macrophages are antigen presenting cells
Only MHC Class I is present
Macrophages plays an important role in both innate (non-specific) and adaptive immune response (specific) by recruiting lymphocytes
Neutrophils are primarily involved in innate (non-specific) immune response with its phagocytic capability
Morphology: Large mononuclear rounded nucleus and are agranulocytes (absence of granules in cytoplasm)
Smaller cells with multi-lobed nucleus and are granulocytes
About 5-7% of circulating WBCs
Most abundant white blood cells; accounts nearly 50-70% of circulating WBCs
Macrophages are found in all tissues.

Neutrophils are normally found in the blood stream and is recruited to the site of infection or injury
Long life span (several months to years). After phagocytosis and killing of pathogen it migrates to the lymph nodes
Short life span (few hours to less than 5 days). After phagocytosis and killing of pathogen it undergo apoptosis and taken up by macrophages
Macrophages reaches during late stages of infection. The primary role of macrophages is in the removal of cellular debris, including apoptotic neutrophils and phagocytosis of large pathogens. 
They are the first immune cells to reach site of infection or injury
Classically activated macrophages requires a priming signal in the form of IFN-gamma via the IFN-gamma R. Alternatively activated macrophages does not require priming but require IL 4 and IL 13
Generally activated upon bacterial or fungal infection; by chemical signals such as IL-8 and are the first immune cells to reach the site of infection
Macrophages are also able to engulf apoptotic neutrophils and make use of the antimicrobial molecules present in their granules.
Neutrophil die after phagocytosis of pathogen and is immediately taken up by macrophages
Macrophages exist in different forms with various names through out the body
Eg: Monocytes in bone marrow/blood
Kupffer cell in liver, Sinus histiocytes in lymph nodes etc
No phenotypic variation or rare.

*IFN=interferon; IL=interleukin
Reference: Silva, Manuel T., and Margarida Correia-Neves. “Neutrophils and Macrophages: The Main Partners of Phagocyte Cell Systems.” Frontiers in Immunology 3 (2012): 174. PMC. Web. 25 Mar. 2018.

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