An antibody is a protein that reacts
against an antigen in an animal-like organism. Antibodies, which can
be found in blood or other body fluids, are used by the immune
system to recognize and block viruses, bacteria, parasites, or fungi.
Importantly, each type of antibody defends the body against a specific class
of antigen. When the antibody mistakes healthy tissue for a harmful substance,
it speaks of an autoimmune disorder.
The most frequent antibody is made up of basic structural units that have
four chains: two light and two heavy. The B lymphocyte is in
charge of synthesizing the antibodies, which can be divided into five different
classes (isotypes) in the case of mammals.
Although the general structure of the antibodies is similar, a certain region
of the protein is highly variable, giving rise to the existence of millions of
antibodies. This part of the protein is called the hypervariable region.
the wide variety of antibodies is produced by combinations of a set of
genetic segments, responsible for encoding various sites of binding to the
antigen. It then undergoes random mutations in this region of the antibody gene,
increasing diversity even further.
Among the numerous types of antibodies, there may be mentioned anti-histological
antibodies (which react against tissue antigens), anti-nuclear
antibodies (attack antigens found on the surface of cell nuclei) and bivalent
antibodies (capable of fixing a pair of corresponding antigen molecules
on its surface), among others.
Immune system diseases
There is a group of diseases that are due to disorders in the immune
or immune system and whose consequences are the suffering of frequent
infections. In some cases they are not very serious but their recidivism could
mean a delicate complication for the patient.
Some of the causes of these diseases can be found in the existence of certain
unusual infectious cancers, in viruses, fungi or some type of bacteria that
directly affects the body's immunity.
These disorders can be due to a decrease in the number of white blood
cells, improper functioning (despite being the amount the body needs)
or other failures of the immune system.
It is worth mentioning that immunodeficiency can occur from the moment of
birth, in cases where it is genetically inherited, or develop over the years due
to certain external factors.
Acquired immunodeficiency, which manifests itself at an advanced age, is
usually caused by a certain disease. In some cases, a minor deterioration is
generated in the defense system, but in others, the most severe, the body's
ability to cope with infection can be destroyed.
One of the best-known infections is that caused by HIV (human
immunodeficiency virus), which is caused by the disease or acquired
immunodeficiency syndrome, known as AIDS. This virus breaks
down white blood cells, making it impossible for them to respond to the threat
of any external infection, making any simple disease a serious problem for the
During childhood one of the main causes of disorders in the immune system is malnutrition. If
a child is malnourished that is less than 80 percent of his or her proper body
weight, the immune system is known to be affected, and if it is 70, the
condition will be severe. This happens because the deficiency of nutrients
caused by this poor diet prevents the body from creating antibodies, weakening
more and more and becoming vulnerable to any threat from the outside.