Immunology under the microscope: knowing what is known

The previous post in this series can be found here.

As a passionate believer in science, I have had many debates over the dinner table or at the bar with those who consider scientific research either unimportant or ineffective. The argument often comes back to “Well, science doesn't know everything!” To say this inherently misunderstands science and scientific research. Firstly, science doesn’t know anything; science doesn’t think or know - it simply is. Science is just what exists, it is everything. Everything must be explicable otherwise it couldn’t exist, even if understanding it is beyond the capability of humanity or any other intelligence. If God exists, He presumably understands Himself and so is explicable, to Him at least. I suppose that when people make the claim that “science doesn’t know everything”, they really mean “scientists don’t know everything”.  This statement is obviously true, we don’t know everything, but it never fails to surprise me how little people often assume we do know. I don’t expect people to understand science in great detail, but it is a great shame that there is so much ignorance of the sheer amount of knowledge that we’ve gathered as a race. I have, in the past, been comprehensively informed that “we still don’t even know how genes work!”, which is very surprising news considering I thought I could explain in atomic detail how a gene is transcribed, translated and expressed as a protein – that is to say: how it works. An unfortunate mistake that many people often make is to confuse the statements “I don’t know this” and “nobody knows this”.

Perhaps this is to be expected; seen from the outside, science probably appears very sporadic: there are long periods where nothing is being discovered and then suddenly there’s a big finding and everyone gets very briefly excited before everything dies down again. This, however, is simply a product of the sensationalist way that it is often portrayed in the mainstream media, in which everything deemed too complicated or insignificant is not reported and things that do make the grade are often over-hyped. Following science in this way is a bit like following literature only by watching Hollywood adaptations of major novels. In fact, science progresses in tiny steps that can seem insignificant on their own but contribute to the field as a whole. Immunology is no different.

Treason in the immune army - betrayed by your own

The previous post in this series can be found here.

So far in my series of posts, I’ve tried to give you an insight into how your immune system is organised into divisions with specific roles: B cells  produce antibodies against pathogens; killer T cells demolish infected cells; and helper T cells act as the battle strategists, determining the tactics that will be used to destroy the invaders. Alongside these high-ranking immune cells are innumerable other footsoldiers that take their orders from T cells and sometimes from the antibodies released by B cells: neutrophils, eosinophils, basophils etc.

In any army there is the odd defector, a rogue agent who changes sides or simply goes it alone, and your immune system is no different. The lowly footsoldiers mentioned above are not capable to acting without orders from higher up and so when a turncoat T or B cell starts to send out treacherous commands that you might be in trouble.  In this post, I’m going to explain the different forms of autoimmunity (when the immune system attacks the body) and allergy (when it attacks innocuous molecules). I will also explain how our understanding of the immune system is starting to allow us to treat these disorders and save or improve countless lives.

Autoimmunity and allergy – T and B cells gone bad

Autoimmune diseases affect roughly one in twenty people in the western world; allergies, far more. Their symptoms are hugely variable and range from mild rashes to fatal anaemia. All are caused by misdirection of the adaptive immune system and are driven by conspiratorial T or B cells. Luckily for you and me, immunologists have been working furiously for the last century or so to unravel the causes behind these disorders and are now starting to produce fairly effective and specific cures. As you might expect, the effect of an autoimmune response depends very heavily upon what is rebelling: antibodies fired out by a B cell, for example, will have a very different outcome to a psychotic killer T cell.