Biological Defense II: The Immune Systems of Vertebrates

Abstract

Vertebrates have two more complex and efficient defense systems than the ones described in the previous chapter. The most sophisticated is the adaptive immune system. The system is capable of creating special proteins, antibodies, that can bind nearly any foreign protein, virus, or bacterium with enormous affinity and specificity, marking them for destruction. After the needed antibody is developed, it is produced in huge amounts and it usually stops the spread of the infection. We consider the system in some detail. There are, however, two major problems related to this systems. First, the system has to distinguish between foreign and own proteins. The second problem is the time needed for the development of antibodies, usually a few days. Over this time, harmful bacteria or viruses can bring a lot of harm to the organism. The second system, the innate immune system, helps in solving both of these problems. It has a few components that provide the first response to the invasion. Although the response is not as efficient as the response of the adaptive system, it is fast. In addition, the innate system participates in the activation of the adaptive immune system.