Immunological Methods | Anthropology Optional for UPSC PDF Download

Introduction

The ability of our bodies and cells to resist invasion by foreign objects, be they cellular, viral, or chemical, is the subject of interest of the increasingly important field of immunology. Like all life processes, the basis for immune reaction can be traced to- gene action. Because of the profound influence of molecular genetics on all cellular studies, an area of genetics known as immunogenetics has developed, which combines the two disciplines. We now know that immune reactions are the result of complex gene regulation in our white blood cells.

What is an Immune Reaction

• To simplify and explain the above content better, immune reactions refer to the way our body responds to foreign substances or cells. There are two major types of immune reactions: blood-type incompatibility and transplantation rejection.
• Blood-type incompatibility occurs when different blood types come into contact, causing an immune response. This is due to the presence of proteins produced by specific white blood cells called plasma cells. These proteins circulate in our bloodstream and react to foreign substances, which is known as the circulating or humoral type of immune reaction.
• On the other hand, transplantation rejection happens when the body recognizes foreign cells (such as in a transplanted organ) and stimulates white blood cells like lymphocytes and macrophages to attack and destroy these foreign cells. This process is referred to as the cell-mediated type of immune reaction.

Antigens and Antibodies

• An immune reaction occurs when a foreign substance or cell, known as an antigen, enters the body and triggers a response from the body's specialized immune cells. These antigens are typically organic materials that are not recognized by the host's immune system. In response to the presence of antigens, the body either produces special proteins called antibodies or increases the number of cells called phagocytes, which actively attack the antigens.
• When antibodies are involved in the immune response, several types of reactions can take place. If the antigen is in a liquid solution, the interaction with antibodies can cause the antigen to settle out of the solution, forming a solid residue. Alternatively, if the antigen is a cell, antibodies can cause the cell to rupture, which is known as lysis. Finally, antibodies can also cause antigens to clump together, a process called agglutination.
• In summary, immune reactions involve a complex interaction between foreign antigens and the host's specialized immune cells. This response can result in the production of antibodies or the increase of phagocyte cells to neutralize and eliminate the antigens from the body through various mechanisms, such as precipitation, lysis, or agglutination.

Circulating Antibodies, Blood Groups and Reaction to Disease

• Antigens and antibodies are closely related; an antigen is a substance that triggers the production of antibodies, while an antibody is a protein found in blood plasma that is produced by the body in response to the presence of a specific antigen. These antibodies, which play a role in immune reactions, are known as circulating antibodies because they circulate within the blood plasma.

The Genetic Basis of ABO Blood Types

• The ABO blood group system is based on genetics. When different blood types are mixed, a clumping reaction, called agglutination, can occur. This happens because individuals with type A blood have anti-B antibodies, while those with type B blood have anti-A antibodies. People with type O blood have both anti-A and anti-B antibodies, and those with type AB blood have no antibodies against ABO antigens.

Genetic Determination of Antibody Molecule

• Biologists have been fascinated by the fact that all plasma or antibody-producing cells in an individual are genetically identical, yet they can produce millions of different antibodies. This allows the body to respond specifically to each antigen that enters, giving each person the potential to produce a vast number of unique antibody molecules. This is especially impressive when you consider the wide range of microorganisms that can infect us, as well as the numerous organic substances and plant materials that many people react to.
• This variation in antibodies is utilized in immunological methods. An antigen is injected into a person, and the resulting antibodies are separated and purified. These antibodies have been studied, and their amino acid compositions have been determined. It has been discovered that antibodies produced by different individuals have varying amino acid compositions in their chains. When these antibodies are injected into an experimental animal, they act as an antigen, and the animal forms antibodies against the human antibody. The antiserum from the animal, which contains antibodies against the human antibody, is then collected.
• With this antiserum, blood samples can be tested to observe the differences in genetic variability among humans. This showcases the incredible diversity and adaptability of the human immune system in producing a wide range of antibodies to protect against various threats.

Conclusion

Immune reactions are essential processes that occur when our body encounters foreign substances or cells, such as during blood-type incompatibility or transplantation rejection. These reactions involve complex interactions between antigens and the host's specialized immune cells, which can result in the production of antibodies and other defense mechanisms. The ABO blood group system is a prime example of the genetic basis of immune reactions, and the immense diversity of antibody production showcases the adaptability of the human immune system in protecting against various threats. As the field of immunogenetics continues to develop, our understanding of these interactions and the genetic factors that influence them will be crucial in improving human health and combating diseases.