Introductory Remarks

Abstract

The Ninth International Histocompatibility Workshop started at a time when the technology for testing B cell alloantigens and information on ten DR alleles and several supertypic specificities had already been well established through the Eighth International Histocompatibility Workshop and spread among the HLA laboratories of the world. The nature and the genetic organization of the supertypic specificities were very much in dispute. A number of antigens belonging to new loci were postulated, and these claims were supported by biochemical evidence for the existence of several different classes of DR-like antigens. However, it was not clear exactly which allotypic specificities reside on which molecules, because most of the biochemical data were obtained using monoclonal antibodies directed at monomorphic determinants. Monoclonal antibodies defining polymorphic HLA determinants were just beginning to appear. It was therefore a logical consequence that one of the major aims of the Ninth Workshop was the utilization of the great potential of monoclonal antibodies for further dissection of the HLA polymorphisms by direct serological testing, as well as by biochemical analysis of molecules precipitated by the same polymorphic monoclonal antibodies. One of the major questions to be resolved was the organization of the HLA-D region. Which loci exist in the D region? Which antigenic specificities are governed by which loci? What is the precise relationship between serologically defined antigens and the HLA- Dw antigens? One of the keys to the understanding of the serology of the D region was to be the definition of the elusive specificity DRw6. At the same time, it was hoped that in the definition of HLA antigens by cellular reagents, the standard procedure of typing with homozygous typing cells (HTCs) could be complemented by proliferating and cytotoxic T cell clones.