Interactions Between Dendritic Cells and Infectious Agents

Abstract

The body is constantly exposed to a remarkable variety of infectious agents, such as viruses, bacteria, fungi, and parasites. The individual pathogens differ with regard to their genetic organization, the tissue of localization and replication, the way of transmission, the mode of replication, the mechanism of causing disease, and the type of host response they elicit. To prevent entry of microbial agents in our body, epithelial surfaces act as a physical barrier. These epithelia comprise the skin and the mucosal linings of the gastrointestinal, respiratory, and urogenital tract. They also secrete antimicrobial substances, including lysozyme, defensins, and various other chemical and biological modulators. However, infectious agents enter the body of the hosts by means of a breach in epithelial surfaces or directly into the circulation. One of the main characteristics of the evolutionary process is to develop highly sophisticated defense mechanisms for survival of human beings and other living organisms in hostile environments. Only when pathogens come in contact with the epithelial barrier or cross the barrier or enter into circulation does the immune system initiate effector mechanisms to eliminate the infectious agent.