Insight on Body Defense Mechanisms and Vaccination [Archives:2001/33/Health]
Marwan Ahmed al-Ghafory
Faculty of Medicine
Ain Shams University, Egypt
There are many different defense mechanisms that protect the body against the foreign micro-organisms and potentially harmful material. Some of these including physical barriers like the skin, phagocytic cells, and certain chemical substances and enzymes
(like those in saliva and internal and external body secretions). This kind of immunity is termed “innate” or ‘natural’ immunity, and these mechanisms are not enhanced by previous exposure to the pathogen, nor they do discriminate between different foreign substances.
Other defense mechanisms, collectively termed are known as “the adaptive immunity”, have components that are capable of distinguishing foreign and the self structures, and are enhanced by previous exposure to the pathogen (hence the concept of vaccination).
When the body is exposed to the micro-organism for the first time, a class of immuno-competent cells “the lymphocytes” become activated and differentiated into another generations of active cells, memory cells and plasma cells . The former become primed by all the details of the organism hence when the body is invaded for the 2nd time these cells immediately involve in immune response by differentiating again into antibody -producing plasma cells. Those produced specific antibodies bind to a certain site on the surface of the antigen ‘the invader’ and the consequent destruction and killing out of the organism follow. Sometimes the organism may be too small to be acted upon by the antibody, and this initiates another line of adapted mechanisms termed ‘cell- mediated immune response”. The mechanism here is so fascinating, as there is a kind of cells called T-HELPER CELLS that mediate this conflict. These cells produce stimulating factors to enhance all immuno -competent cells to act at different levels of assistance and promotion until they get rid of the invader.
Depending on the above we can understand the disaster of “AIDS” (acquired immune deficiency syndrome) as it destroys the T -HELLPER CELLS , and hence no resistance ensues. The concept of adapted immunity and acquired resistance to the infection led the scientists to ” vaccination ” procedures. The first population who used vaccination in protection were the Chinese about 590 AD against the small pox and plague ‘black death’. That is simply through inoculating the body with the pathogenic organism in an attenuated form so as to enhance the adaptive immune response. When the same organism invades the body, it defends the body against those offending organisms sufficiently and clears the body from the foreign conqueror.