Even in high school, we receive a rudimentary knowledge of the immune system.  In more advanced classes, we learn of the various white blood cells that perform in specific and individual ways.  Some for virus fighting.  Some for fighting bacteria.  Some for fighting allergies, some for inflammation and some for fighting various foreign bodies.  The largest number of WBCs generally are the Neutrophils to fight bacteria.  I suppose mainly because we receive so much bacteria in our respective environments from surfaces, food, water, etc.  Often, after the virus fighters (T-Cells) have weakened the entire immune system, then bacteria and the resultant infections occur and neutrophils will increase to fight bacteria.  We would like to think that the body has no bacteria at all.  Wrong.  As distasteful as it may seem, when we die, the body must be treated quickly with preservatives (embalming fluid) because bacteria will take over and destroy the tissues quickly.  Where did the bacteria come from?  It is inherent in our bodies.  Of course, it is kept in check by the circulating WBCs being constantly on-guard and destroying the bacteria every second of blood circulation.  If the immune system is compromised or weaken, infections can occur.  Another distasteful thought.  If you have ever peeled back a scab and you noticed pus coming from the wound, pus is nothing more than WBCs and specifically Neutrophils fighting bacteria in the wound.  Pus is nature's way to prevent infections from cuts.

Those that are HIV Positive have few or no T-Cells or lymphocytes, the WBC that fights virus.  The very WBC that's supposed to fight virus, the AIDS virus attacks T-Cells!  Not too many years ago, a person with the AIDS virus had an approximate ten year timeline to live if they were in otherwise good health.  At least now days, the so called protease inhibitor prescriptions "trick" the virus so T-Cells are not being attacked as much and AIDS patients have extended their lives greatly.

Even those of us that are HIV Negative, the T-Cells or lymphocytes will still wane periodically but not go to zero.  They are our virus fighters and have nothing to do with bacteria.  Also, the reason that antibiotics don't work for viruses, they are a different critter.  Antibiotics are for fighting bacteria not virus.  When the T-Cells are low in numbers and the virus is out there, this is usually when you get the flu or a cold from a virus floating through the air.  Since bacteria are generally larger in size, they precipitate or fall to the ground or surfaces.  Of course, unless someone with a bacterial infection sneezes right in your face, you won't inhale bacteria.  Thus, the good reason to wash hands and keep surfaces clean.  Unfortunately, the various viruses are so small they have the ability to float through the air.  Further, they spread and make the public sick by simply inhaling them.  Many foreign countries wear surgical type masks to avoid viruses from being inhaled or from spreading them to others.  A process not yet caught-on in the United States much.  There is research on-going about antivirals but not effective for all viruses yet.     

Lab tests can reveal the percentages of your WBC numbers when having a CBC.  There are reference ranges to see where an individual registers. A lot can be told by these percentages of the various WBCs.  Too many Neutrophils can be an indication of an infection somewhere in the body.  Too few can be an indication of a weak immune system to fight bacteria in the event of a bacterial issue or potential infection.  Too many T-Cells can be an indication of a virus or in some cases leukemia.  Too few T-Cells can mean you are going to susceptible to virus, colds or flu. The body has an amazing ability to sense what WBC it needs at any given time.  Elevated Eosinophils can be an indication of allergies or an inflammatory response.  Monocyte and Basophil numbers also tell your doctor much about inflammation.

All this being said, there are ways to modulate or regulate your immune system in which I will report in another blog.  Just because the epidemic levels of flu are out there, it doesn't mean you're going to get it if you do the right things to boost your immune system as needed.