SPECIFIC IMMUNITY (ACQUIRED, ADAPTIVE OR INDUCIBLE)

 

INTRODUCTION: Acquired immunity refers to that immunity which a person develops during his lifetime. Acquired immunity is the surveillance mechanism that specifically recognizes foreign antigens and selectively eliminates them, and on re-encountering the antigen has an enhanced response also sometimes referred to as memory.

CHARACTERISTICS OF ACQUIRED IMMUNITY: There are six major characteristics of acquired immunity: 1) Specificity 2) Inducibility 3) Diversity 4) Memory 5) Distinguishing self from nonself and finally 6) Self-limiting

HUMORAL IMMUNITY: Immunity based on antibodies is called as humoral immunity. Antibodies are produced by B subset of lymphocytes. probably the most formidable type of immunity.  This form of immunity is conveniently subdivided into that which is actively acquired and that which is passively acquired. The humoral immunity protects against circulating extracellular antigens such as bacteria, microbial exotoxins and viruses in their extracellular phase; that is, antibodies normally interact with circulating antigens but are unable to penetrate living cells. In active immunity the individual synthesizes his own antibodies, whereas in passive immunity the individual receives these antibodies from some other individual, either a human or a lower animal. Both active and passive types may each be further divided into natural and artificial. The artificial types are those that result from intervention by physicians. Passive immunisation

ACTIVELY ACQUIRED IMMUNITY: A degree of naturally acquired active immunity results from any infection from which a person recovers, whether the illness is serious or subclinical. During the illness the individual receives an antigenic stimulus which initiates antibody production against that specific pathogen. On a subsequent visitation by the same or an antigenically related pathogen, these antibodies will assist in the defense of the body. Because many microbes produce diseases with a high morbidity, this is not a very satisfactory way of developing immunity. This problem could be overcome by producing safe and potent vaccines or toxoids that are being used to induce active immunity. 

RELATED;

1.  ACTIVE IMMUNISATION  

2.  PASSIVE IMMUNITY  

3.  BCG IMMUNISATION  

4.  IMMUNOGLOBULINS

5.  MEDICAL MICROBIOLOGY

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