Immunity and immunizing agent...........

This presentation elaborates the basic concept of immunity and immunizing agent.

1. IMMUNITY AND IMMUNIZING AGENTS PRESENTED BY MISBAH KAWOOSA Mentor: Dr. SHABANA Maqbool .

2. Immunity Derived from Latin word “Immunis” freedom from nonself

3. Definition: It is the ability of the body to recognise,destroy and eliminate antigenic material(bacteria, virus, protein etc.) which is foreign to its own. ( ref.Park ) The ability of the body to resist almost all types of organisms or toxins that tend to damage the tissues and organs.

4. Historical Aspect Study of immunity/concept about immunity dates back to 1000 A.D. Its concept was first observed by Chinese. They began to practice a form of immunization by drying and inhaling powders derived from the crusts of small pox lesions. The first clinical description of immunity which arose from a specific disease-causing organism is probably Kitab fi al- jadari wa -al- hasbah ('A Treatise on Smallpox and Measles', translated 1848 written by the  Islamic  physician  Al- Razi in the 9th century. In the treatise, Al Razi describes the clinical presentation of smallpox and measles and goes on to indicate that exposure to these specific agents confers lasting immunity (although he does not use this term

5. The first scientist who developed a full theory of immunity was  Ilya Mechnikov  after he revealed  phagocytosis  in 1882 . Around the fifteenth century in  India, the Ottoman Empire, and east Africa, the practice of inoculation (poking the skin with powdered material derived from smallpox crusts) became quite common .  This practice was first introduced into the west in 1721 by  Lady Mary Wortley Montagu

6.  Edward Jenner introduced the far safer method of deliberate infection with cowpox virus, (smallpox vaccine), which caused a mild infection that also induced immunity against smallpox. By 1800 the procedure was referred to as  vaccination .

7. Classification/Types of immunity/Two arms of immunity Innate Immunity (Non specific, natural or non adaptive immunity) Acquired Immunity (Specific or adaptive immunity)

8. INNATE IMMUNITY Here antigenic exposure is not required Not specific Non Adaptive Onset of response-immediate Found in both invertebrates and vertebrates. ACQUIRED IMMUNITY Antigenic exposure is required Specific Adaptive Delayed response Found only in vertebrates

9. INNATE IMMUNITY Genetic or constitutional Individual immunity Species related Race related Age related Physiological barrier at the portal of entry Skin Mucous membrane

10. Conjunctiva Auditory meatus Mouth Nose Urethra and vagina Humoral Cellular

11. ACQUIRED IMMUNITY Active immunity Passive immunity

12. ACTIVE IMMUNITY Active immunity can be acquired in three ways: f ollowing clinical infection e.g., chickenpox, rubella and measles. following subclinical or in apparent infection e.g., polio and diphtheria Following immunization with an antigen which may be a killed vaccine, a live attenuated vaccine or toxoids.

13. PASSIVE IMMUNITY By administration of an antibody- By transfer of maternal antibodies across the placenta. Human milk also contains protective antibodies By transfer of lymphocytes, to induce passive cellular immunity( this procedure is in experimental stage)

14. ACTIVE IMMUNITY Develops after active participation of host to generate the immune response. PASSIVE IMMUNITY 1. There is no active participation of host.     2. Needs lag period of 7-10 days. 2.Doesnot need lag period 3. Onset of action- delayed 3. Immediate onset of action 4 . Duration of action- prolonged 4. Duration of action-shorter 5 . Induced by-exposure to antigen 5.induce by – cytotoxin T cell 6 . Chance of Hypersensitivity Development-No 6. Yes 7. Immunological memory-yes 7. no    

15.   ACTIVE IMMUNITY     CELLULAR HUMORAL     NATURAL ARTIFICIAL NATURAL ARTIFICIAL                

16.   PASSIVE IMMUNITY     CELLULAR HUMORAL     NATURAL ARTIFICIAL NATURAL ARTIFICIAL                

17. CELLULAR IMMUNITY Cellular immunity plays a fundamental role in resistance to infection. Cells of Acquired immunity: T-Lymphocyte B-Lymphocyte

18.       POINTS   CELLULAR   HUMORAL 1. Produced by T-Cell Ig 2. Function Concerned with intra cellular organisms Extracellular organism 3. Virus infected cell kills - 4. Tumor cell kills - 5. Graft cell kills - 6. Large parasite kills - 7. Neutralization of virus No Yes 8. Opsonisation of virus No Yes 9. Neutralization of toxin No Yes 10. Hypersensitivity TYPE IV TYPES I, II, III, V,VI  

19. IMMUNE RESPONSE PRIMARY RESPONSE : It occurs after first exposure to an antigen. Mature B cells are activated by antigen Antibody appears in blood usually 7-10 days after first exposure to antigen IgM antibody first appears and then IgG or IgA,appears. Antibody appears in small amounts. Maximum in 2 months, then declines.

20. SECONDARY RESPONSE It occurs on re-exposure to the same antigen. Memory B cells are activated by the antigen. Antibody appears in blood on subsequent exposure to the same antigen . Mostly IgG antibody which is of much higher level and remains high for longer period.

21. ANTIGEN: Substance that binds with antibody and/or antigen binding receptor on lymphocyte . IMMUNOGEN: Substance that induces an immune response . ‘All immunogens are antigens but all antigens are not immunogen ’

22. ANTIBODIES: These are the immunoglobulin that react specifically with the antigen that in the first place stimulated their production. IMMUNOGLOBULIN : These are glycoproteins made up of heavy and light polypeptide chains. ‘All antibodies are immunoglobulins but all imunoglobulins are not antibodies ’

23. HERD IMMUNITY It is defined as “the level of resistance of a community ore group of people to a particular disease. Herd immunity implies group protection beyond that afforded by a protection of immunized individual. It is seen that if 70-80% of people of the community is immunized, the community remains free of the infection. The 30% who could not be immunized get the benefit of immunity by just being the member of the immunized community.

24. That is, it concerns the freedom from infection of individuals of individuals within a herd by sole virtue of the influence of the herd structure on the transmission among individuals. Production/Achievement of herd immunity: NATURAL PROCESS : Following attack of the disease Following in apparent or subclinical infection.

25. ARTIFICIAL PROCESS: Immunization Merits of immunity: Provides immunological barrier to the spread of disease. The epidemic wave declined with a build up of herd immunity following natural infection. If the herd immunity is sufficiently high, the occurrence of an epidemic is regarded as highly unlikely.

26. IMMUNIZATION: It is defined as a technique by which immunizing agents are introduced into the body for the production of antibody to prevent disease.

27. IMMUNIZING AGENT

28. VACCINES Vaccine is an immune-biological substance designed to induce specific protection against a given disease. It stimulates the production of protective antibody and other immune mechanisms.

29. TYPES:

30. LIVE VACCINE: Some vaccines contain live, attenuated microorganisms. Many of these are active viruses that have been cultivated under conditions that disable their virulent properties, or that use closely related but less dangerous organisms to produce a broad immune response. Although most attenuated vaccines are viral, some are bacterial in nature. Examples include the viral diseases yellow fever , measles, mumps, and rubella, and the bacterial disease typhoid. The live  Mycobacterium tuberculosis  vaccine developed by Calmette and Guerin is not made of a contagious strain but contains a virulently modified strain called "BCG" used to elicit an immune response to the vaccine.

31. The live attenuated vaccine containing strain  Yersinia pestis  EV is used for plague immunization. Attenuated vaccines have some advantages and disadvantages. They typically provoke more durable immunological responses and are the preferred type for healthy adults. But they may not be safe for use in immunocompromised individuals, and on rare occasions mutate to a virulent form and cause disease.

32. KILLED VACCINE Some vaccines contain inactivated, but previously virulent, micro-organisms that have been destroyed with chemicals, heat, or radiation .  Examples include the polio vaccine, hepatitis A vaccine, rabies vaccine and some influenza vaccines

33. CHARACTERISTIC KILLED VACCINE LIVE VACCINE No. of doses multiple single Need for adjuvant yes no Duration for immunity shorter longer Effectiveness of protection lower greater Immunoglobulins produced IgG IgA and IgG Mucosal immunity produced Poor yes CMI produced Poor yes Residual virulent virus in vaccine possible no Reversion to virulence no possible Interference by other viruses in host no possible Stability at room temp high low

34. Toxoid Toxoid  vaccines are made from inactivated toxic compounds that cause illness rather than the micro-organism .  Examples of toxoid-based vaccines include  tetanus and   diphtheria . Toxoid vaccines are known for their efficacy .  Not all toxoids are for micro-organisms; for example,  Crotalus atrox  toxoid is used to vaccinate dogs against rattlesnake bites .

35. CELLULAR FRACTIONS : Vaccines in certain instances, are prepared from extracted cellular fraction, e.g. Meningococcal vaccine from the polysaccharide antigen of the cell wall,pnemococcal vaccine from the polysaccharide contained in the capsule of the organism and hepatitis B polypeptide vaccine.

36. COMBINATIONS If more than one kind of immunizing agent is included in the vaccine, it is called mixed or combined vaccine. The aim of such types of vaccines is: Simple administration Reduces cost Minimizes the no. of contacts of the patient with the health syste m

37. IMMUNOGLOBULINS

38. IMMUNOGLOBULIN PREPARATION Normal Human Ig It is an antibody rich fraction, obtained from a pool of at least 1000 donors. WHO has laid down definite standards for it’s preparation: Preparation should contain at least 90% intact I gG It should be as free as possible from IgG aggregates.

39. All IgG subclasses should be present. There should be a low IgA concentration The level of antibody against at least two bacterial species and two viruses should be ascertained.

40. Example: Normal human Ig is used to prevent measles in highly susceptible individuals. To provide temporary protection( upto 12 weeks) after hepatitis A infection for travellers to endemic area.

41. Human specific immunoglobulin is prepared from the plasma of individuals with have high antibody levels against a specific infection. These individuals are either recovering from the specific illness or have been recently immunised . Specific immunoglobulin preparations are available for: hepatitis B - used following needle stick injury tetanus - used in suspected tetanus infection rabies - used in suspected rabies infection herpes zoster - used to protect susceptible children

42. ANTISERA OR ANTITOXINS The term antiserum is applied to materials prepared in animals. Is nonhuman blood serum containing monoclonal or  polyclonal antibodies that is used to spread passive immunity to many diseases. he most common use of antiserum in humans is as antitoxin or  antivenom  to treat  envenomation .

43. Example:- ATS- Prophylactic use-in case of tetanus prone wounds Curative use- to cure tetanus. ARS- As pre and post exposure prophylaxis

44. ADS } both prophylactic as well as curative purpose AGS } both prophylactic as well as curative purpose.