Essay on Immunology (1520 Words)

Immunology is a branch of science under broad spectrum of Biology which deals with the study of remarkable defense mechanism of the body (completely in vertebrates and partly in invertebrates) against harmful foreign invading agents or particles and to protect body from pathogenic microorganisms and- some severe diseases.

We are always exposed to a vast environment which contains different types of components out of which a great variety of pathogenic microbes like viruses, bacteria, fungi, protozoa, unicellular and multi-cellular parasites and infectious parti­cles are present, which can cause diseases when they enter within our body.

If these foreign pathogenic agents are allowed to invade and multiply enormously, they will kill their host gradually and eventually. Normal individuals face different types of problems for a short time or for a comparatively longer period of time.

But internal system is able to generate a huge number and variety of cells and molecules which are capa­ble to recognize and can eliminate the foreign intruders. Body can get rid of this unwanted situ­ation due to the presence of immune system.

Immunology received its priority due to gradual increase of different types of diseases and sufferings of mankind. The Latin term ‘immunis’ meaning “exempt”, is the source of the English word immunity, meaning the state of protection from infectious disease.

Perhaps the earliest written reference to the phenomenon of immunity can be traced back to Thucydides, the great historian of the Peloponnesian war. He wrote a book in 430 B.C regarding plague in Athens. He mentioned that only those who had recovered from the plague could nurse the sick people because they had already been exposed to the disease and would not be affected again.

Thousand and thousands of people died due to small-pox, a severe disease. People, who could escape death, had to live with pock marks for rest of their life. In this context, Chinese discovered a crude practice of infecting young children with small-pox. Scabs from the pocks on the skin of an infected person put into the skin of infants. Children became resistant to small-pox who could come out of the disease. This technique was called variolation.

The news of protecting children against small-pox gradually spreaded to central Asia and to Turkey. In 1718, Lady Mary Wortley Montagu, the wife of the British ambassador to Constanti­nople, observed the positive effects of variolation on native population and she had applied the technique to her own children.

The technique of variolation [in Latin, variola means small-pox] spreaded rapidly in England and the technique was improved a lot by the English physician Edward Jenner in 1798. Further death of Queen Anne’s son due to small-pox made people aware of this technique. It was also spreaded rapidly in America, where George Washington ordered all his troops should be innoculated in 1776.

Later on, in 1774, Benjamin Jestly, an English farmer adopted the technique of variolation to his son by using a dried scab material from cattle infected with small-pox. Further, Edward Jenner, in 1798, professional­ly learned about the use of cow-pox scabs from humans and started to investigate the truth behind it. He conducted a number of experiments and confirmed that exposure to dried cow-pox scabs from humans could protect humans from small-pox.

Jenner introduced his technique of vaccination (in Latin, vacca means cow) which gradually started to replace variolation technique. Jenner explained the postulation of introduction of fluid from a cow-pox pustule into people. To make his postulation right, Jenner inoculated an eight year old boy with fluid from a cowpox pus­tule. Later on, he intentionally infected the child with small-pox but the child did not develop small-pox.

Jenner’s technique of vaccination by inoculat­ing cow-pox against small-pox became popular day by day and spreaded quickly throughout Europe. In 1958, the World Health Organization (WHO) eradicated small-pox by mass vaccination technique. As a successful attempt of this effort, small-pox was completely eradicated from the earth by 1980.

After Jenner’s successful discovery of vacci­nation it took another 100 years to raise another milestone in the field of this aspect.

As an advancement, in France, Louis Pasteur in 1879 studied on the disease cholera. He started his experiment on a bacterium, the causaline agent of a disease of chickens called fowl cholera. The bacterium is now called Pasteurella multicida. Pasteur was able to make a culture medium where this bacteria could grow. He injected bacteria into chickens and invariably they died.

During a sum­mer vacation, he handover the duty to continue the experiment to his assistant, Charles chamber-land. But he discontinued the continuation of experiment on chickens. After returning from a summer vacation, he injected some chickens with an old culture of the bacterium.

As a result of this consequence, the chickens became ill but they escaped death. From this findings Pasteur came to a conclusion that aged bacterium loose their level of virulence and became weakened with respect is their paths genicity. He noticed this effect minute­ly, administered it again and again and suggested this less virulent strain of bacteria as vaccine in honour of Jenner’s discovery and naming.

After establishment of general principle of vaccination, Pasteur extended his findings towards vaccination of other infectious diseases. He first administered a vaccine against anthrax, caused by the bacteria, Bacillus anthracis. Some vaccinated sheep and unvaccinated sheep were exposed to virulent, Bacillus anthracis.

Ultimately, as a result of this experiment, he noticed all vacci­nated sheep lived, whereas all unvaccinated ani­mals died. So with this attempt Pasteur opened a door of new era. Therefore, Louis Pasteur can be considered as founder of the science of immunology.

Gradually, new steps were added to this branch of immunology by different workers. In 1894, Emile Roux was successful by immunizing patients suffering from the disease diptheria by an injection of serum from the blood of a horse immunized against diptheria. The technique was named as passive immunization. This can be done as the horse serum contains antibodies against tetanus toxin.

In 1882 Eli Metchinikoff first demonstrated immunity in invertebrates and later in mammals that cells could eat foreign material, meant for body defense against invading microorganisms, called phagocytes. In 1904, Almorth Wright (in England) and Joseph Denys (in Belgium) explained that antibodies could coat bacteria and promote their destruction by phagocytes, called as opsonisation.

As the study of immunology proceeds day by day, different workers research on different dis­eases revealed new lines in immunology. In 1901 Emil von Behring was awarded Nobel prize for his work on antitoxin (production of antibodies against toxins).

Again, in 1905 Robert Koch was awarded Nobel prize for his detailed study on tuberculosis. In 1908, Paul Ehrlich and Eli Metchinikoff received Nobel award for their unique theme on immunology that immune sys­tem will not evoke any response against self-body components.

Another aspect of immunological study, i.e., anaphylaxis was discovered by Charles Richet by immunizing dogs against a toxin from sea-anemone. He awarded the Nobel prize in 1913. Jules Bordet won the Nobel prize in 1919 for his unique discovery regarding complement.

With the advancement of further study in the field of immunology, in 1930 Karl Landsteiner was awarded Nobel prize for his discovery of principle of Blood-grouping. He identified the presence of self-antigen (agglutinogen) and antibody (agglu­tinin) within human blood. His efforts resulted in the development of blood transfusion principle.

Gradually in 1960, Peter Medawar and Macfarlane Burnet won the Nobel prize. They confirmed that immune system recognizes foreign material but they will not recognize own cell as non-self. Their efforts were further extended by Burnets obser­vation regarding the ability of immune system to identify material-clonal selection theory. Rodney Porter and Gerald Edelman describe the chemical structure of antibody molecules and awarded Nobel prize in 1972.

A milestone is added in the field of immuno­logy by Rosalyn Yalow and S. A. Berson in 1960 to determine the levels of insulin-anti-insulin com­plexes in diabetics. In 1977, some years after Berson’s death, the significance of the technique was acknowledged by the award of a Nobel prize to Rosalyn Yalow. After this, a new era of immunology has been introduced by three immunologists in the field of immunogenetics.

George Snell, Jean Dausset and Baruj Benacerraf added their contribution. George Snell developed geneti­cally defined mouse strains and determined the existence of genes that control the process of graft rejection. Jean Dawset developed techniques to identify the molecules found on the surface of human cells. Baruj Benacerraf observed the inher­itance of an organism’s ability to make antibodies against some molecules.

Furthermore, in 1984, Niels Jerne won Nobel prize with Georges Kohler and Cesar Milstein for their Novel work like discovery of the principles on the production of monoclonal antibodies by Kohler and Linstein and theories on specificity, development and control of the immune system.

Susumu Tonegawa was awarded Nobel prize in 1987 for generation of antibodies which not only recognize but also bind with foreign molecules. Donnal Thomas and Joseph Murray were awar­ded the Novel prize in 1990 for their unique method of organ transplantation by grafting a also Thomas was successful to irradiate leukemia kidney between identical twins. Not only this but cells of a sufferer by bone marrow transplantation.