April 29 has been declared International Day of Immunology.
It would not be an exaggeration to say that most people would not even understand the meaning of the word, let alone the significance of this concept.
The immune system is the body’s way of protecting itself against bacteria, viruses and other organisms that constantly surround us and are hell-bent on invading and multiplying within our body.
That it is an excellent protective mechanism is witnessed by the relatively small number of people who are really bothered by these threats for the greater part of their lives.
Unfortunately, however, sooner or later our defences are down and the battle is lost, resulting in pneumonias and other infections around the body.
So what constitutes the immune system? This is a complex construct, consisting of several individual elements, all of which are essential and which combine together to provide the body with the protection it requires.
Firstly, we find in the blood a number of proteins (immunoglobulins) which have the very specific property of combining with bacteria to render them harmless.
Vaccination boosts these proteins and makes them more abundant and effective. Anyone who has had the misfortune of having a car accident, or even of simply treading on a rusty nail, will know that an essential line of treatment is to have an injection of anti-tetanus serum to be protected against this dangerous infection.
A second line of defence depends specifically on special cells (lymphocytes). These come in various shapes and forms and exhibit correspondingly varying activity.
Some are best qualified to deal with specific chronic infections (like tuberculosis). Some are essential for boosting the immune response in general by interacting with other cells to produce immunoglobulins.
Yet another line of defence is constituted by cells whose function is to mop up all debris that is considered extraneous and foreign. These cells (macrophages) are constantly on the look-out, picking up bacteria and destroying them.
They also interact with other cells to stimulate the immune response in general. It is almost 100 years ago that Bernard Shaw famously highlighted the role of these cells when a character in his play The Doctor’s Dilemma advised a general panacea: “Stimulate the macrophages”!
Unfortunately, not everybody has a normally functioning immune system all the time. Sometimes babies are born with a deficiency of one or other of the immune components, rendering them prone to chronic infections.
Premature infants are also deficient in this department. Much more commonly, we can have episodes in our life when our immune system becomes weak and incapable of functioning properly.
Viruses have a special predilection for depressing the immune response: the virus responsible for AIDS has perfected this technique of disabling the immune cells of the body, rendering it weak and succumbing readily to various severe infections.
The list of conditions which may depress the immune response is quite long. It includes advanced disorders of several body organs like kidney and liver; it includes serious disease like advanced cancer, or even the use of drugs or radiations to treat cancer; it includes the ubiquitous diabetes; it includes old age itself, when most of our systems start on a gentle decline.
There is a thriving trade in unproven remedies that are touted to improve the function of the immune system. In general, a healthy body does not require any special remedies which a good diet, exercise and avoidance of exposure to toxic elements like smoking and alcohol cannot upply. But it is difficult to prove the effectiveness of the alternative methods of treatment, including multivitamins and concoctions of various minerals which are readily accessible across the counter.
Perhaps most intriguing of all is the capacity of the immune system to turn, occasionally, against the body itself, resulting in a process known as auto-immune disease.
In this situation, cells of the immune system invade and often destroy other organs. A typical example of this is Type 1 diabetes, which tends to affect younger individuals and children.
In this condition, those cells which normally produce insulin are destroyed with resulting high level of sugar in the blood. In others, the thyroid gland may be attacked and partially or completely destroyed, resulting in the absence of the thyroid hormone necessary for normal daily metabolic function.
In spite of this aberration, it may be stated that we cannot livewithout a normally functioning immune system, which hums away quietly without our noticing it, and it is only when thingsgo wrong that we suddenlywake up with a start to notice the aberration.