Difference between Active and Passive Immunity: Explaination

Ans. Below are the examples of Active Immunity:

• During the third trimester of pregnancy, the baby receives antibodies (IgG) from the mother.
• IgA antibodies, as well as other Abs, are found in breast milk.
• After rabies exposure, for example, an immunoglobulin injection is administered.

Ans. Below are the examples of Passive Immunity:

• Passive immunity is induced when a body is exposed to pathogens in ordinary life.
• The body is exposed to a portion of the pathogen contained in a vaccine, such as a live attenuated vaccination (MMR).
• Toxins from a pathogen that have been deactivated (Corynebacterium diphtheriae toxin, Clostridium tetani toxin)
• A portion of a bacterial cell (Bordetella pertussis and streptococcus pneumonia).

Ans. When given in an attempt to encourage a more robust response with more memory cells, it is known to be hyper-irritating to the immune system. Mercury is a good example.

Ans. When a host is exposed to viruses or germs, the host generates antibodies, whereas passive immunity occurs when the host gets antibodies from another source.

Ans. A vaccination can also provide passive immunity by supplying antibodies or lymphocytes that have already been produced by a human or animal donor. Vaccines are often given through injection (parenteral administration), although some are also given orally or nasally (in the case of flu vaccine). So COVID Vaccination provides us with Passive Immunity.

Ans. Innate immunity is present from birth and is inherited from the parents.

(i) It is non-specific.

(ii) It consists of the following types:

• Physical barriers prevent the entry of microorganisms in the body e.g. skin, the mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts.
• Physiological barriers prevent microbial growth in the body, e.g. acid in the stomach, saliva in the mouth and tears from the eyes.
• Cellular barriers phagocytose and destroy microbes. For example, some WBCs like Polymorphonuclear Leukocytes (PMNL), monocytes and natural killer cells (type of lymphocytes) in the blood as well as macrophages in tissues.
• Cytokine barriers are virus-infected cells, which secrete proteins called They protect uninfected cells from further viral infection.

Ans. The science that makes a study of diseases is called pathology, though in a broad sense it includes diagnostic, prophylactic and curative measures too. Pathology is a study of diseases of all kinds though we will confine ourselves to the diseases caused by a pathogenic organism, the reaction of the host as shown in the form of symptoms, the diagnosis made through a study of their symptoms, aetiology of the pathogenic organism and finally steps undertaken to cure the host of its diseases, by eradicating and if it is not possible, by controlling the pathogen. In this way, the study of biology helped us to control infectious diseases.

Ans. (a) Innate & acquired immunity

Innate immunity, also called inherent, natural, non-specific immunity, comprises all those defence elements with which an individual is born & which are always available to protect a living body. It acts on many organisms and does not show specificity, e.g. Lysozyme present in secretions such as tears, catalyzes the hydrolysis of molecules in the cell walls of bacteria & interferon induces an antiviral state in non-infected cells. They act as physiological barriers & check the growth of many pathogenic microorganisms. Acquired immunity, also called adaptive or specific immunity, is the immunity obtained either from the development of antibodies in response to exposure to an antigen, as from vaccination or an attack of infectious diseases or from the transmission of antibodies from mother to foetus through the placenta.

(b) Active & passive immunity

Active immunity is acquired by catching & surviving an infectious disease or by vaccination with a weakened form of the disease which makes the body form antibodies. Whereas passive immunity is conferred by transfer of immune products like antibodies etc. from another individual

Ans. Vaccination and immunisation The principle is based on the property of memory of the immune system.

(i) Vaccination is the process of introduction of weakened or inactivated pathogens or proteins (vaccine) into a person to provide protection against disease.

(ii) Immunisation is a process by which the body produces antibodies against the vaccine (primary response) and develops the ability to neutralise pathogens during actual infection (secondary response), i.e. the body becomes immune to that antigen or infection.

(iii) Vaccine generates memory B and T-cells that recognise the pathogens on subsequent exposure and produce an intense immune response.

(iv) In case of requirement of quick immune response like tetanus infection, preformed antibodies are injected into the patient. This is called passive immunisation.

(v) Recombinant DNA technology has produced antigenic polypeptides of the pathogen in bacteria or yeast. This allowed large scale production of vaccines, e.g. hepatitis-B vaccine from yeast, etc.

Ans. Secondary lymphoid organs provide the sites where lymphocytes interact with the antigen and proliferate to become effector cells, e.g. spleen, lymph nodes, tonsils, Peyer’s patches of small intestine and appendix. The spleen is a large, bean-shaped organ that contains lymphocytes and phagocytes. It acts as a filter to trap blood-borne microbes and contain a large pool of erythrocytes. Lymph nodes are small solid structures along with the lymphatic system. Their function is to trap microorganisms or other antigens that enter the lymph and tissue fluid. Mucosal Associated Lymphoid Tissue (MALT) is formed of the masses of lymphoid tissue, lining the mucosa of respiratory, digestive and urogenital tracts. About 50% of lymphoid tissue in the human body is formed by MALT.

Ans. Since, the secondary immune response is based on the memory of the primary response,i.e. first encounter with antigen. The second generated immune response is faster, having a higher affinity for antigen, and therefore more intense than the primary immune response.

Ans. Certain types of leukocytes (such as PMNL- neutrophils, monocytes) and natural killer cells are two types of cells that act as ‘cellular barriers’ to provide innate immunity in humans

Ans. The abnormal response of an immune system in which it fails to recognise ‘self' and ‘non-self’ and start destroying its own cells and molecules is called autoimmune disease. Rheumatoid is an example of autoimmune disease which destroys articular cartilage and fuses bones

Ans. Tetanus is a disease caused by Mycobacterium tetani. A person with cuts and bruises following an accident is administered tetanus antitoxin because this toxin contains antibodies against the pathogen. This inactivates the pathogen (called passive immunity).

Ans. (i) Thymus is a primary lymphoid organ of the immune system. Maturation of lymphocytes occurs in it. T-cells produced in the bone marrow get mature in the thymus and are released from here.

(ii) T-cells are released from the thymus, upon maturation. They themselves do not produce antibodies but help B-cells to produce them. They are also responsible for Cell-Mediated Immune (CMI) response.

Ans. Types of immunity systems in humans are:

(i) Innate immunity, acquired immunity or humoral immunity system and cell-mediated immunity system.

(ii) Cells mediated immunity is so called as it involves specialised cells, the T-lymphocytes. Humoral immunity is so called because it includes antibodies, which are found circulating in body fluid, the blood (humours-body fluids).