Meet Your Immune System

Meet Your Immune System

The immune system consists of distinct cellular populations dispatched throughout
the body to protect us from invading pathogens, such as viruses, unfriendly bacteria,
fungi, and parasites. Immune cells communicate with each other through chemical
mediators that regulate and interface with many other bodily systems. The main
organs of the immune system include:

• The bone marrow (from which all the cells of the mature immune system are initially derived)

• The thymus, whose function is to produce mature T cells

• The spleen, which serves as our immunologic filter of the blood and is made

• up of various immune cells (including T cells and NK cells)

• Lymph nodes, which are found throughout the body; they house the cells that

• produce antibodies, the proteins that inactivate identifiable foreign

• trespassers in the body, and they filter the bodily fluid known as lymph

There are two fundamental branches of the immune system: innate and adaptive.
The innate, or cellular immune system, attacks any entity considered foreign (like
infectious bacteria), and is evolutionarily ancient, literally prereptilian. In other
words, it will go after any bacteria, any pathogen, any invader at all.

As we evolved in complexity as mammals, however, we needed something a bit
more specialized. The result was the adaptive immune system, which recognizes an
attacker as potentially harmful and then remembers that pathogen’s specific identity
so that the body’s defense can be better targeted next time and the attackor doesn’t
have a second chance to inflict a disease state. One such pathogen is the influenza
virus, against which we mount a defense using antibodies, or “immune arrows,” as
immune specialist Dr. Michael Rosenbaum calls them (pers. comm.), to attack and
corner the offender.

In a healthy immune system, both branches and all of their cells are well
equipped to fight the hordes of invaders (bacteria, viruses, fungi, and parasites) that
are looking to set up shop inside us. Because immune cells reproduce so rapidly and
some of them have such a short life span (just a few days), our bodies need to invest
substantial amounts of energy in keeping the system functioning smoothly. Good
nutrition makes this possible. A well-nourished immune system fights off invaders,
including cancer, using a coordinated sequence of events.

First, foreign pathogens that invade the body are recognized by specific white
blood cells known as macrophages, whose responsibilities include scavenging and
surveillance. Dendritic cells, which are a specialized type of macrophage, identify
the invader, and display its name on the dendritic surface, then summon “higher
authorities” to help deal with it. These higher authorities are the lymphocytes. The
first lymphocytes on the scene are called T-helper cells, which work to coordinate
the overall response. If the pathogen is already known to the immune system, the Thelper
cells will likely summon the cytotoxic T cells (“killer T cells”) to help finish
off the enemy. If an unknown threat, such as cancer cells, should appear, elite forces
known as NK (natural killer) cells are called into action. NK cells, part of our innate
immune function, specialize in dealing with new threats. And unlike T cells, they
don’t need to have had a previous encounter with an invader to go after it; they will
attack anything that appears to present a danger. For this reason, NK cells are the
most active of all of the immune cells when it comes to facing down cancer. Once
the immediate threat has passed, suppressor T cells do the job of calming the
immune system down.

Adequate nourishment for all components of the immune system is essential for
ensuring that all of these jobs are carried out with maximum effectiveness. Nutrient
insufficiency in the face of a bodily threat inevitably leads to immune weakness,
increasing our susceptibility to cancer occurrence or recurrence.