The Immune Team's Innate System

               Any good defense system requires some type of early response to meet an invader when it first breeches the borders.  In past weeks, an overview of the innate and adaptive immune system provided a thirty-thousand-foot view of our immune defense while a survey of the communications system explained how millions of cells across our body coordinate an effective defense.   Today, you will learn more about the early responders and some of the messengers which coordinate this early response before activating the next wave of defense, the adaptive response.  A better understanding of the innate arm of the immune system allows better preparation and diminishes fear of our fallen worlds microbial enemies.

As soon as an invader breaks through your skin, your sinuses, your GI tract, or wherever they break in, your immune system must act fast.  The speed of defense can determine whether victory or defeat results or at least how much damage accumulates from the battle.  The Innate system acts as your first responder, stepping into the battle immediately before you even consciously realized what is happening.  With this fast response, countless attacks are repelled without your awareness of anything having happened. This is happening daily if not right now in your body.  Only later, after the battle continues does the adaptive system responds next in the counterattack against invaders.

Upon first blush, the innate immune system may appear somewhat blunt and primitive,

but without this foundation the rest of the system doesn't have time to respond and doesn't get primed for action.  The innate system starts with antigen presenting cells, the sentinels.  These include a variety of different cells:  dendritic cells, monocytes, macrophages and even melanocytes, the skin cells that determine skin color.  Don't worry about the cell names right now.  Basically, their job is to recognize pathogen patterns and activate other immune cells. Different pathogens, the microbial invaders, present different markers on their surfaces which allow our immune system to recognize them as invaders.  Once our cells recognize the invader, they use messengers to alert other immune cells.   

After recognition and the communication system is activated, an acute phase response occurs.  This response sends inflammation messengers near and far to other immune cells. Coagulation proteins increase, triggering blood clotting that blocks the invading microbes from traveling too far into our bodies.  A chemical system called the complement system activates to kill yet more invading enemies.

               Simultaneously, some of these innate system cells start eating the invaders. These cells chew invaders up and spit out pieces in a process called phagocytosis. Then other cells can arrive on the battlefield and recognize the invader from these fragments.  Specific phagocytic Cells on the team include dendritic cells, macrophages, and neutrophils. Dendritic cells sit in tissues throughout the body like watchmen waiting for an invader to trigger them and set off the alarms.  Macrophages and neutrophils act more like mobile sentries roaming the bloodstream and tissues looking for invaders.  These cell types then eat the invader and alert other cells. 

               Activation through antigen or pathogen patterns is not the only means of activating the innate system.  Natural Killer cells respond to the signals of our infected cells. When a virus infects a cell, the cell alerts others to the invasion.  Natural killer cells respond to this alert by killing the infected cell before it releases more viruses.

Another step in the innate system involves mast cells.  These interesting cells reside throughout our body tissues and serve as sentinels.  Once activated they release a multitude of messengers especially histamine.  These messengers activate nearby immune cells, as well as activating and  recruiting distant immune cells.

                As the innate system revs up and mounts its attack, its signals activate the next arm, the adaptive system.  Future articles will introduce you to the adaptive systems team and weapons, but for now, you can be reassured that without you even knowing it is happening, your innate system is patrolling your body’s borders, repelling invasion attempts day in and day out.  Awareness of this God given gift calms fears of infectious threats lurking nearby.  Understanding the system better in Immune Prepper 1010 allows you to optimize this early response system and improve its success rate.  When you are ready to go beyond these basics, our Immune Prepper 101 can take you a step further in preparing for the 2020’s and beyond.