Antibodies passive acquired immunity

Passive Acquired Immunity Antibodies from a human or animal source are administered to the patient. 

The theoretieal baekground whieh underlies immunity to infection has been discussed in detail in Chapter 14. Immunity to infeetion may be passively acquired through the receipt of preformed, proteetive antibodies or it may be aetively acquired through an immune response following deliberate or accidental exposure to microorganisms or their eomponent parts. Aetive aequired immunity might involve either or both humoral and cell-mediated responses. 

Immune systems in animals and plants are quite different. There are two types of immune systems in animals (1) innate, so-called non-specific or passive immunity (2) adaptive, so-called specifically acquired , active, or cell-mediated immunity. Innate immunity is based on barriers to infectious agents and adaptive immunity is based on multiplicative and specific antibody release after contact with an antigen (infectious agent). The so-called memory cells in animals respond to secondary contact with an antigen. 

When antibodies produced in one body are transferred to another to induce protection against disease, it is known as passive immunity. It can be acquired naturally i.e. in foetus receiving mother s antibodies through placenta or artificially by administration from outside in the form of antisera containing antibodies. 

Short-term immunity may be achieved by passive vaccination, or the transfer of protective antibodies into the recipient. Vaccination is currently being explored as a therapeutic approach for inducing needed immune responses in individuals who have acquired a disease (e.g., cancer or Alzheimer s disease)... 

Passive immunization is accomplished by transferring antibodies from a resistant to a susceptible host. Passively transferred antibodies confer a temporary but immediate resistance to infection, but are gradually catabolized by the susceptible host. Once passive protection wanes, the recipient becomes susceptible to infection again. Passively transferred antibodies can be acquired by the recipient either transplacentally and transcolostrally as in neonates, or by injection of purified antibodies from a resistant donor into a susceptible recipient. 

Passive immunity is induced by injection of serum taken from an individual already immune to a particular antigen it can also be acquired by the transfer of maternal antibodies to offspring via the placenta or breast milk (seecolostrum). Active immunity tends to be long-lasting passive immunity is short-lived. See also autoimmunity. 

Artificially acquired passive immunity When antibodies made by other hosts are introduced into a new host, e.g., via mother s milk or shots of gamma globulin. 

Naturally Acquired Passive Immunity When antibodies made by another individual are given to a host, e.g., in mother s milk, without intervention by man. 

Once an individual has become immune through previous infection, vaccination, or by passive transmission of maternal antibody, these specific defenses effectively control most viral and bacterial pathogens. Depletion of the CD4+ T-lymphocyte population, as occurs in acquired immunedeficiency syndrome (AIDS) leads to a general reduction in immune competence and an increased susceptibility to infectious and neoplastic disease (22). Similarly, IgA deficiency can result in increased risk of respiratory tract infection (23). 

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