Types of immunity
Chapter 2 Social Pharmacy Notes 2.1 Demography and Family Planning, 2.2 Mother and child health, 2.3 Importance of breastfeeding, 2.4 Ill effects of infant milk substitutes and bottle feeding 2.5 Overview of Vaccines, 2.6 Types of immunity 2.7 Immunization 2.8 Effect of Environment on Health 2.8.1 Water pollution 18.104.22.168 Importance of safe drinking water, waterborne diseases 2.8.2 Air pollution 2.8.3 Noise pollution 2.8.4 Sewage and solid waste disposal 2.8.5 Occupational illnesses 2.8.6 Environmental pollution due to pharmaceuticals 2.8.7 Psychosocial Pharmacy: Drugs of misuse and abuse – psychotropics, narcotics, alcohol, tobacco products.
Immunity can be natural or artificial, innate or acquired = adaptive, and either active or passive.
Active natural (contact with infection):
develops slowly, is long term, and antigen-specific
Active artificial (immunization):
develops slowly, lasts for several years, and is specific to the antigen for which the immunization (Vaccine) was given
Passive natural (transplacental = mother to child):
develops immediately, is temporary, and affects all antigens to which the mother has immunity
Passive artificial (injection of gamma globulin):
develops immediately, is temporary, and affects all antigens to which the donor has immunity
The innate immunity system is what we are born with and it is non-specific; all antigens are attacked pretty much equally. It is genetically based and we pass it on to our offsprings
Adaptive or Acquired Immunity
Lymphocytes come in two major types: B cells and T cells.
- B cells are produced in the stem cells of the bone marrow; they produce antibody and oversee humoral immunity.
- T cells are non-antibody-producing lymphocytes which are also produced in the bone marrow but sensitized in the thymus and constitute the basis of cell-mediated immunity.
There are two fundamental adaptive mechanisms: cell-mediated immunity and humoral immunity.
Macrophages engulf antigens, process them internally, then display parts of them on their surface together with some of their own proteins. This sensitizes the T cells to recognize these antigens.
T cells are primed in the thymus, where they undergo two selection processes. The first positive selection process weeds out only those T cells with the correct set of receptors that can recognize the MHC molecules responsible for self-recognition. Then a negative selection process begins whereby T cells that can recognize MHC molecules complexed with foreign peptides are allowed to pass out of the thymus.
Cytotoxic or killer T cells (CD8+) do their work by releasing lymphotoxins, which cause cell lysis.
Helper T cells (CD4+) serve as managers, directing the immune response. They secrete chemicals called lymphokines that stimulate cytotoxic T cells and B cells to grow and divide, attract neutrophils, and enhance the ability of macrophages to engulf and destroy microbes.
Suppressor T cells inhibit the production of cytotoxic T cells once they are unneeded, lest they cause more damage than necessary.
Memory T cells are programmed to recognize and respond to a pathogen once it has invaded and been repelled.
An immunocompetent but as yet immature B-lymphocyte is stimulated to maturity when an antigen binds to its surface receptors and there is a T helper cell nearby (to release a cytokine). This sensitizes or primes the B cell and it undergoes clonal selection, which means it reproduces asexually by mitosis. Most of the family of clones become plasma cells. These cells, after an initial lag, produce highly specific antibodies at a rate of as many as 2000 molecules per second for four to five days. The other B cells become long-lived memory cells.
- Complement fixation (proteins attach to antigen surface and cause holes to form, i.e., cell lysis),
- Neutralization (binding to specific sites to prevent attachment—this is the same as taking their parking space),
- Agglutination (clumping),
- Precipitation (forcing insolubility and settling out of solution), and other more arcane methods.
Difference between active immunity and passive immunity
|Sr.no||Points||Active immunity||Passive immunity|
|1.||Mediated by||1. Antigen containing preparations imparts active immunity. Or Mediated by antibodies produced by a person’s own cells||1. Antibody containing preparations imparts passive immunity Or Mediated by antibodies produced outside the body.|
|2.||Development||2. Immunity develops slowly and lasts for a longer period.||2. Immunity develops quickly and lasts for a short period.|
|3.||Purpose||3. It is used for long term prophylaxis.||3. It is used for prophylaxis and also for curative purposes.|
|4.||Origin||4. Produced actively by the host’s immune system.||4. Received passively by the host, no participation by the host’s immune system.|
|5.||Induction of Immunity||5. Induced by infection or by using immunological products. E.g. Vaccines.||5. Achieved by introducing readymade antibodies.|
|6.||Immunological memory||6. Immunological memory is present||6. Immunological memory is absent.|
|7.||Use||7. Not useful to immunodeficient hosts.||7. Useful to immunodeficient hosts.|
|8.||Heredity||8.No inheritance||8. Maybe acquired from mother.|
|9.||Side effect||9. No side effect||9. body may react to antisera.|
Immunizing agents or products:
The substance or live organisms that when administered into the body of a susceptible person make him immune against one particular disease are called immunizing agents or immunological products.
3. Antisera or Antitoxins
Vaccines are immunological products derived from different biological sources to provide protection against a specific disease.
a) Live vaccines:
1. Live attenuated vaccines contain live organisms which have antigenic properties but have lost their disease-producing capability.
2. Live vaccines are available for e.g measles, poliomyelitis, yellow fever, BCG for tuberculosis etc.
b) Inactivated (killed) vaccines:
1. The disease organisms are killed or inactivated and then purified extract is injected into the body containing antigens.
2. It is available in combination with toxoids. E.g. pertussis component is killed in DPT vaccine whereas diphtheria and tetanus are as toxoids, salk viral vaccine for polio,
a. Toxoids are used to produce endotoxins, this endotoxin is detoxicated and is used as a vaccine.
b. It is injected into the body to stimulate the production of antibodies against toxins.
3. Cellular fraction:
a. Instead of the whole organism a part or fraction of the organism is used for vaccine production.
b. It can be the cell wall of the organism, polysaccharide antigen as in meningococcal meningitis or pneumococcal vaccine.
4. Combined vaccines: / mixed vaccines:
a. If any of the two types of vaccines are combined with each other and given in one dose it is called combined vaccination.
b. These are used to reduce the cost of production and to increase the ease of administration. e.g. DPT vaccine.
5. antisera or antitoxins:
The term antiserum is applied to materials prepared in animals’ example: horses are used for passive immunization against diseases like tetanus, diphtheria, botulism etc.
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Manisha Yogesh Chaudhari is working as an Assistant Professor at Kokan Gyanpeeth’s Rahul Dharkar College of Pharmacy, Karjat, Maharashtra, India. She has worked with Pfizer and Flamingo Pharmaceuticals. She is actively involved in Books writing, Review, and research paper writing as well as actively involved in contributing towards academic literature