Question

Which are the two types of immune system in a human body. What it means in the name of ‘cell mediated’ and ‘humoral’ immunity?

Answer 1

Hint: The immune system is a remarkably adaptive defense system that has evolved in vertebrates to protect them from invading pathogenic microorganisms and cancer. Functionally an immune response can be divided into two related activities, namely recognition and response. Immune recognition is remarkable for its specificity.

Complete answer: Immunity is the resistance of the body against antigens and infections or pathogenic organisms and their biological products. It has both nonspecific and specific components. The nonspecific component of innate immunity is a set of disease resistance mechanisms that is not specific to an antigen. Phagocytic cells play an important role in many activities of innate immunity. The innate immunity provides the first line of defense during a critical period just after the host’s exposure to a pathogen.
Therefore, the innate immunity is a type of immunity which is present at the birth and changes little throughout the lifetime of the individual. The cells and molecules of the innate system are highly responsible for the primary stages of expulsion of the microorganisms and may give rise to inflammation.
Acquired immunity or adaptive immunity is the ability to recognize and selectively eliminate specific foreign microorganisms and molecules. The adaptive immune activities are reactions to specific antigenic challenges.
Acquired immunity can be divided into two types. They are active and passive immunities. Active immunity is acquired by natural infections caused by viruses and bacteria. Passive immunity is the acquisition of immunity by receipt of preformed antibodies rather than by active production of antibodies after exposure to antigen.
Serum obtained from blood provides the active molecule such as antibodies. Because the antibodies are carried by the body fluids their immunologic events are known as humoral immunity.
In cell mediated immunity, immunologic events contributed by T cells and B cells. T cells are derived from thymus and B cell or B lymphocytes are derived from bursa of fabricius in birds. Hence it is called cell-mediated immunity.

Note: Vaccination is the best known and the most successful application of immunological principles to human health. First aim in vaccination is to provide protective immunity by stimulating a memory response to an infectious microorganism using a non-toxic antigen preparation. It is important to produce immunity of the suitable kind, namely antibody or cell mediated immunity. The aims of vaccination are to induce memory in T and B lymphocytes through the injection of a non-virulent antigen preparation.