My Immune System is Killing Me

Most living organisms have immune systems that help them stay alive and healthy. But there are times when the immune response overshoots the boundary and becomes dangerous and even lethal to “self “.

We know this because during this pandemic, many people are dying not only because of weak immune system but due to overactive immune response. A physiological phenomenon called “cytokine storm” that was unknown 50-60 years ago, is now commonly talked about during the coronavirus pandemic.

Before we talk about the abnormal, lets learn a little bit about the normal immune system.

Immune system is both “innate” (that we are born with) and acquired (we develop it over our lifetime). It is also classified as cellular (where the main players are cells) and humoral (where the main actors are proteins called antibodies).

Innate immune system recognizes tissues that are “self” and rejects or destroys those that are “foreign”. A good example is blood group. An individual who inherits type A blood from the parents will destroy type B blood cells if they are infused. Type B blood cells are “foreign” to this individual’s immune system.

We are familiar with the acquired immunity that is induced by vaccinations or our exposure to various substances that we come across during day to day life.

There are many different types of cells in our blood and in our tissues that form the cellular immune system. Their job is to recognize “foreign” substances (e.g. germs, viruses), organize and attack to repel such foreign invaders. These cells can also call upon special proteins (antibodies) to help them fight off the invading germs.

About half a century ago, scientists discovered other special proteins in the blood called “cytokines” that were invoked by the immune system to fight infections and other maladies.

The full force of the immune system: innate, acquired, cellular, humoral and the cytokines are essential to keep us safe and healthy during an infection.

But it has become well known that at times the body’s response overshoots and its own immune system goes rogue causing harm and even death. This has been happening with some of the COVID-19 patients. It is important to diagnose this phenomenon because its treatment is quite different than treatment of the viral infection.

A COVID-19 patient who suddenly develops respiratory collapse, heart failure, decreased blood pressure and decline in the liver and kidney function; is most likely a victim of the “cytokine storm” i.e. the overzealous immune system. Such a condition is treated with immune suppressive drugs to calm down the immune system. This seems counter-intuitive because we know that immuno-suppressed individuals are at greater risk during the pandemic.

While we are hard at work to develop effective treatment to eradicate the virus, physicians are also alert and managing the way body is reacting to this infection.

The currant treatment trials include antivirals such as lopinavir/ritonavir or remdesivir that are expected to work directly on viruses by killing them and/or preventing their replication.

The convalescent plasma (proteins from the blood of those who have fully recovered) is being used to disable and weaken the coronaviruses.

Drugs like steroids and hydroxychloroquine/ chloroquine seem to reduce inflammation in the lungs and help improve oxygenation.

Drugs like tocilizumab are being used to calm the overactive immune system when a cytokine surge is suspected.

Vaccines, once fully developed and tested, will help us develop immunity against future outbreaks. Until then, we hope and pray that the virus passes over us and if we do get infected, it is a mild case and that our immune system behaves as it should not get overly excited.