OxyFile #449

Ozone & The Immune System - Part 2 

A.J. Lanigan

I should be interestin that the macrophage is the oldest know 
immune cell. The hydra (a jelly-fish type invertabrate) has only 
this cell as its defense. Vertabrates (like us) have many types of 
immune cells along with the macrophage. Not only will this guy do 
some killing. He will clean up behind himself. He will also clean 
up behind you. (with all this oxytherapy, there are a lot of dead 
things left laying around) 

Phagocytosis is mediated by macrophages and polymorphonuclear 
leucocytes. Phagocytosis involves the ingestion and digestion of 
the following: 

* microorganisms 
* insoluble particles 
* damaged or dead host cells 
* cell debris 
* activated clotting factors 

There are several stages of phagocytosis: 

1. Chemotaxis 
This is the movement of cells up a gradient of chemotactic 
factors. It may be directly induced by a substance such as C5a, 
produced as a result of complement activation. It can also be 
indirectly induced as a consequence of release of preformed 
mediators within mast cells by the action of C3a or C5a e.g. 
eosinophil chemotactic factor, or neutrophil chemotactic factor. 
Leukotrienes, produced by the metabolism of mast cell arachidonic 
acid, are also chemotactic. 

2. Adherence 
This works reasonably well for whole bacteria or viruses, but less 
so for proteins or encapsulated bacteria. In order to deal more 
effectively with encapsulateed bacteria, antibodies directed 
against the capsule enable the phagocytic cells to ingest the 
organisms, using their Fc receptors(see below). 

3. Pseudopodium formation 
This is the protrusion of membranes to flow around the "prey". 

4. Phagosome formation 
Fusion of the pseudopodium with a membrane enclosing the "prey" 
leads to the formation of a structure termed a phagosome. 

5. Phago-lysosome formation 
(well kiss my grits, you mean the macrophage practices 
The phagosome moves deeper into the cell, and fuses with a 
lysosome, forming a phago-lysosome. These contain hydrogen 
peroxide, active oxygen species (free radicals), peroxidase, 
lysozyme and hydrolytic enzymes. This is known as the oxidative 
burst, and leads to digestion of the phagolysosomal contents, 
after which they are eliminated by exocytosis. Some peptides 
however, undergo a very important separate process at this stage. 
Instead of being eliminated, they attach to a host molecule called 
MHC class II and end up being expressed on the surface of the cell 
within a groove on the MHC molecule (antigen presentation). 

The speed of phagocytosis can be increased markedly by bringing 
into action two attachment devices present on the surface of 
phagocytic cells: 

Fc receptor: which binds the Fc portion of antibody molecules, 
chiefly IgG. The IgG will have attached the organism via its Fab 
site. Complement receptor: the third component of complement (C3) 
also binds to organisms and then attaches to the complement 

This coating of the organisms by molecules that speed up 
phagocytosis, is termed 'opsonization', and the Fc portion of 
antibody, and C3 are termed 'opsonins'. 

And all of you thought that the German's first discovered