The histocompatibility system and human disease.

The histocompatibility system and its associations with human diseases have been described. Although these associations remain unexplained, they represent an important step forward in the search for basic causes and mechanisms of diseases. Further studies may lead to better classifications of diseases and to an increased understanding of basic biologic processes, of etiologies of many important diseases, and of relationships between genetic and environmental susceptibility to disease. However, at the present time histocompatibility studied have little value as diagnostic or prognostic tests in clinical medicine, aside from their obvious usefulness in matching tissue donors to recipients.