Mask + Social Distancing + Hand washing + Ventilation + Innate Immunity = No Virus

The innate immunity is the part of our immune response we have at birth.  Innate immunity does not require prior exposure by infection or vaccination.  Innate immunity includes the exterior barrier first line of defense and the interior second line of defense.  The innate exterior first line of defense barriers includes the skin and the mucous membranes.  The innate interior second line of defense includes phagocytic white blood cells (devouring WBC) and natural killer white blood cells (NK).  For innate defense against viruses the NK cells and a chemical messenger called interferon are very important.  Both NK cells and interferon are discusses in a previous post.

Failure of innate immunity signals the 3rd Line of Defense.

If the innate immunity’s first and second line of defense fail, then the pathogen’s invasion has breached all of the innate defenses.  The third line of defense is signaled to respond with a counterattack.  The third line of defense is a learned response.   It requires training that is acquired by infection or vaccination.  The cells receiving training are a special type of WBC called lymphocytes.  The pathogen is brought to base camp (such as lymph nodes) and the new lymphocyte recruits are trained to respond to this specific pathogen.  This training typically takes 5-10 days.  During this time the patient will be sick and may have symptoms. 

The counterattacking lymphocytes involved in the 3rd line of defense include B and T lymphocytes.  The B lymphocytes are trained to produce antibodies that specifically bind to the pathogen.  In viral infections, if the antibody binds to the virus particle PRIOR to the virus subversively entering a host cell the antibody can neutralize the virus.   Special Forces of T lymphocytes called Cytotoxic T Lymphocyte (CTL) are trained assassins that directly kill cells infected with the virus.

These specifically trained lymphocytes, both B and T, produce clones of themselves.  These cloned cells have the same abilities as the parent lymphocytes.  This army of B and T cells attacks the pathogen and clears it from the patient.  The patient will notice a decrease in symptoms and begin to feel better.   The majority of this cloned army is short-lived and once the infection is cleared these cells die.  However, a small portion of this highly trained experienced army remains behind as memory B and T cells that become part of the surveillance system looking for that pathogen if it dares to return.

The 3rd Line of Defense

  • Is not present at birth
  • It is not needed if the innate immunity is successful
  • It is a learned response that takes 5-10 days (typically)
  • It produces memory (that may last weeks to years)
  • It is specific and will only recognize the exact same pathogen (if virus mutates it is not recognized)

The “Chalk Talk” Video below explains the 3rd Line of Defense