The last few years have witnessed major developments in molecular biology which have had a significant impact on biomedical knowledge. As a result new concepts in cell biology have emerged, new etiologic agents have been discovered, and new drugs have become available. Furthermore, the world of mediators, cytokines, and humoral factors has enlarged considerably in a relatively short period and this has modified our views of diverse physio pathologic processes as well as opened up new therapeutic prospects. In addition, recent technologic advances have revolutionized our diagnostic methodology...