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A Phagocyte

Abscesses: Phagocytosis, Pus and Healing

A Bacterium in Armor

This is one of those projects which deals with a topic so disgusting that it is sure to be a hit at any presentation! As disgusting as they, abscesses are common, and like so many common things, are hardly understood. You have the opportunity to advance the cutting edge of medical science rather easily. Up to now, a few college students have only "scouted" this project superficially. It would not be inserted into this website had it not shown signs predicting positive results. Alas, the instructor retired before the project was completed.

Bacterial infections can manifest themselves in several ways. The most widespread is the systemic infection where the bacteria are found throughout the body. One of the most localized is that of the abscess, which, while disgusting, is something very good from the view of your body - it has caged the pathogen rather than allowing it to wander at will throughout the body doing damage. Thus abscesses are a natural strategy used to fight infection.

But how do abscesses work? In essence and using a lot of street language, a white blood cell encounters a bacterium, and yells out that there is a stranger among us. Its "yell" is in the form of a class of biochemicals called cytokines, which beckon other white blood cells to come to the point of infection and surround the enemy.

Most often all this goes unnoticed because the first few white blood cells phagocytize (engulf and digest) the invaders. and the battle is finished. But every so often an invader has a trick or two or three up its sleeve (ref), and cannot be killed by the "phagocytes" (literally: "eating cells"). Those bacteria continue to merrily grow sprewing out whatever they do that is bad for you. More and more white blood cells congregate at the site trapping the pathogens in the center (this is what is assumed and is one thing needing experimental testing). The mass of eager but ineffectual phagocytes builds up to the point that you can see them as a blob of pus under the skin (if the abscess is close to the body surface).

Of course, most of us humans, do something to break open the pustule and the often foul smelling pus comes out - carrying with it both phagocytes as well as many of the harmful bacteria. However, breaking them open is not always a good idea because the scratching or squeezing needed to break them open often introduces new types of bacteria which may have other tricks in their repertoire and lead to a different kind of infection to make matters go from bad to worse.

However, if an abscess is allowed to continue unbroken, the body is usually able to defeat the pathogen and finally the abscess subsides and everything goes back to normal after a week or two. Usually! If it didn't, we wouldn't be here as our cave ancestors would have long ago died out. Now how in the world does the body go about defeating the bacterial infection and mopping up the battlefield to get back to normal? So much is known about how things form, but not how the body deals with it in a natural way.

It is important to know how nature has learned how to do such things as healing an abscess because we might be able to augment nature's ways with subtle little tweaks here and there that do not lead to increased numbers of resistant mutants. Remember that all these antibiotic resistant mutants we now have are the result of only 60 years of medication. Nature has been fighting disease for billions of years - and we are here as the successful result of all the tricks that nature has learned, including phagocytosis, antibodies, complement, and fever (ref), and cannot be killed by the "phagocytes" (literally: "eating cells"). So let's see what is in an abscess: what is pus, and from that we can wonder how that pus is eventually "mopped up" and the scene of the crime gets back to normal.

The abovementioned college students went through a major medical center's hospital collecting pus samples, and then attacked a number of veterinary clinics to do the same knowing that cats are very abscess prone after fights among themselves. What the students found to their surprise was that the pH of pus was almost always acidic - centering in the 4.5 to 5.5 range. That is hardly a physiological pH of 7.3. Presumably, the build up of acid came about because most bacteria convert their foods into acid byproducts.

In a lunchtime "sit-down" with several world-class experts in infectious disease, the students pummelled the experts with questions about how white blood cells could ever be responsible for healing an abscess. What in the body, they asked, could work in that acidic environment, which, by the way, most bacteria find quite palatable.

It was at this time that the author of this page discovered that under pH 6 most bacteria became unable to produce their capsules. These are, in street terms, like outer clothes, and like clothes protect the body inside from the environment. But, as you know, outer clothes are not absolutely needed to live. So a bacterium that cannot make its capsule, swims around in its "undies" (endotoxin layer or "LPS" for lipopolysaccharide, or O-antigen (ref)), which are likewise not necessary for life. Thus you can have bacteria that are "streakers," swimming in the nude. Most of the laboratory strains of E.coli in schools are totally uninhibited swimmers. Anyway, now that you are getting the picture of how bacteria dress, let's get back to the capsule, also known as the K-antigen (K is from the German "Kapsul"). The K-antigen can be composed of any of perhaps as many as 150 different types of acidic polysaccharide. Thus to continue the analogy, while we people are restricted to wool, cotton, some synthetics, silk, and a few other fibers for our outer clothing, bacteria have a might wider assortment of fibers to choose from. Actually they cannot choose, because what they wear is specified by what sort of K-gene they are endowed with. But the gist of all this is that many types of K-antigen protect their bacterial owners from phagocytosis.

Thus you can see that in acidic pus the bacteria aren't wearing their capsules because they cannot make them under acidic conditions. Thus they are susceptible to phagocytosis - EXCEPT that the acidic environment doesn't seem agreeable to the phagocytic abilities of the surrounding white blood cells. And therein lies your project: "...it doesn't seem..." But where's the published research? There isn't any! Perhaps medical science has jumped to an erroneous conclusion thinking that phagocytes cannot tolerate acidic conditions. Maybe all that pus is not just a stew of dead phagocytes and bacteria. Maybe most of the phagocytes are dead, but it is known that there are many different types of phagocytes, and perhaps one or several types are still operative at acidic conditions. How else could the debris of the abscess ever be cleaned up if no type of phagocyte could tolerate those conditions?

What the college students found was that about 5% of the phagocytic activity of pH 7.3 still existed at pH 5.0. If the pH were returned to 7.3, the activity rose to about 10% of the original indicating that at least two types of phagocytes with these previously undescribed characteristics were present: one type could operate both at pH 5.0 and at pH 7.3; the other type could not operate at pH 5.0 BUT was not killed, and regained activity at pH 7.3. This experiment was reproduced in triplicate.

One of the hurdles that these students had to overcome was how to adjust the pH's so as to not shock the white blood cells (they used cells from horses). One cannot merely drop the pH to 5.0 by dripping in HCl because where the drop of acid hits the solution, it is VERY acidic and may instantly kill any cells in that vicinity. Thus pH's were always adjusted by dialyzing the cell suspension against a solution of the desired pH. Never, under those conditions could the cells be subjected to "over shoot." Centrifuging down the cells and resuspension in new medium of the desired pH was not done because we found that mere centrifugation killed 10% or more of the cells each time. But dialysis of cells in serum against pH-adjusted serum maintained 100% viability as tested with vital dyes.

WHAT NEXT?

Intermediate pH's were not tested, and should be a next step perhaps incorporating the following methodology:

A new method for changing the pH's from 7.3 to whatever and back needs to be developed. One suggestion that was made was to get the phagocytes at pH 5.0 to eat small bits of paramagnetic material (these are available, by the way - usually sold chemically bonded to antibodies so surf for "magnetic antibodies"). These bits are not "iron" as shown here, because it rusts rapidly - especially when colloidal in size, but rather are made of some non-corrodable alloy.

Once the phagocytes have a few of these bits in their vacuoles, they can be stuck to a petri plate placed above a magnet. Then the plate can be rinsed free of non-magnetized cells, bacteria and whatever else, and then flooded with serum of a different pH.

Once the magnet is removed from under the plate, the cells can start moving around again to do phagocytosis of bacteria, for example. If you want the cells back again, put the magnet under the plate, and dump the liquid off, and replace with new liquid. Almost as simple as "cake."

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