Life And Death Of A Macrophage Cell (Macrophage)

My name is Macrophage the macrophage.

I was named Macrophage by my friends who feel there is no other name for me.

Some of them even wanted to call me Super Phage or Big Eater.

We are white blood cells within tissues produced by the division of monocytes.

Our cells are large about 21 micrometers in diameter, still one-fifth of an ovum.

The human ovum measures approximately 100 micrometers in diameter and is the biggest cell.

We often have an elongated irregular shape that reflects our amoeboid wandering nature.

There may be many of us in one region but we are not contiguous.

We display our inclusions only as a result of substantial phagocytic activity.

The Monocytes and we are phagocytes acting in both:

1. Non-specific defenses (innate immunity)

2. Specific defense mechanisms (adaptive immunity) of humans.

Our role is to:

1. Phagocytose (engulf and then digest) cellular debris and pathogens either as stationary or as mobile cells

2. Stimulate lymphocytes and other immune cells to respond to the pathogen.

We move by action of amoeboid movement.

When a white blood cell enters the damaged tissue through the endothelium of a blood vessel (a process known as the leukocyte extravasations), it undergoes a series of changes to become a one of us macrophages

Monocytes are attracted to a damaged site by chemical substances through chemotaxis triggered by a range of stimuli including damaged cells, pathogens and cytokines released by us already at the site.

At some sites such as the testis, we have been shown to populate the organ through proliferation.

Unlike short-lived neutrophils, we survive longer in the body up to a maximum of several months.

An important role of us the macrophages is the removal of necrotic cellular debris in the lungs.

Removing dead cell material is important in chronic inflammation as the early stages of inflammation are dominated by neutrophil granulocytes which are ingested by us if they come of age.

The removal of necrotic tissue is handled by our fixed macrophage cells which will stay at strategic locations such as the lungs, liver, neural tissue, bone, spleen and connective tissue ingesting foreign materials such as pathogens recruiting more of us if needed.

When I ingest a pathogen, the pathogen becomes trapped in a phagosome which then fuses with a lysosome.

Within the phagolysosome, enzymes and toxic peroxides digest the pathogen.

However some bacteria such as Mycobacterium tuberculosis have become resistant to these methods of digestion.

We can digest more than 100 bacteria before we finally die due to our own digestive compounds, usually after a period of several months.

A Little Information on the Macrophage

Macrophages (big eater) are cells produced by the changes of monocytes in tissues.

Human macrophages are about 21 micrometers (0.00083in) in diameter.

Parts of a Macrophage:

1. Pathogens
2. Phagosome
3. Lysosomes
4. Waste material
5. Cytoplasm
6. Cell membrane

Life cycle of a macrophage:

When a monocyte enters the outside damaged tissue through the endothelium of a blood vessel, a process known as the leukocyte extravasation, it undergoes a series of changes to become a macrophage.

Monocytes are attracted to a damaged site by chemical substances through chemotaxis triggered by a range of stimuli including damaged cells, pathogens and cytokines released by macrophages already at the site.

At some sites such as the testis macrophages have been shown to populate the organ through proliferation.

Unlike short-lived neutrophils, macrophages survive longer in the body up to a maximum of several months.

TABLE OF CONTENT

Chapter 1 Story of Macrophage

Chapter 2 Life Cycle of Macrophage

Chapter 3 Formation of a Macrophage

Chapter 4 Death of a Macrophage

Chapter 5 Tuberculosis