Genetic Control of IgE immune Response

Abstract

Plenty of factors that interact each other, are involved in the development of diseases. It is feasible to simplify the model of pathogenesis and elucidate the factors involved if they are divided into genetic and environmental factors. Some diseases develop under the control of a single factor, e.g., a single environmental factor for the development of injuries or carbon monoxide toxicosis; a single genetic factor for the development of color blindness or hemophilia. However, most diseases are classified under both environmental and genetic factors. A typical example is the development of Reiter's disease. When it became endemic in a limited population in the navy, all the individuals who developed Reiter's disease had bacillary dysentery. Furthermore, individuals with HLA-B27 showed higher risk compared with those without HLA-B27 (1). In this case, Schigella dysenteriae was an environmental factor, whereas HLA-B27 was a major genetic factor for the development of the disease. Interaction between a single genetic factor and a single environmental factor is observed not only in determining the susceptibility to certain diseases but also in determining the resistance to diseases or clinical phenotypes. In this connection, schistosoma japonica acts as an environmental factor for post-schistosomal liver cirrhosis, whereas HLA-DR2-Dwl 2-DQwl halotype acts as a *Author to whom all co~Tespondence and reprint requests should be addressed.