Thus, it has been shown that certain H antigens predispose certain individuals to certain diseases. George Snell discovered the genetic factors that determine the possibilities of transplanting tissue from one individual to another. It was Snell who introduced the concept of H antigens. Jean Dausset demonstrated the existence of H antigens in man and elucidated the genetic factors regulating their formation. Baruj Benacerraf showed that genetic factors intimately related to the genes that determine an individual's unique constitution of H antigens actually regulate the interaction among the various cells belonging to the immunological system and are thereby important to the strength of an immunological reaction.
Every individual is unique.
This is true even with regard to the many details of the body's structure. Through studies on the relatively simple red blood cells, for example, it has been possible to demonstrate the presence of different blood group antigens. The formation of the antigens found in the cell membrane is regulated by information found in the cell's genes. Thus, the characteristics of the individual, as well as of his cells, are genetically determined. If cells with different surface properties come into contact with each other within an organism, which is what happens in the case of tissue transplantations, a reaction takes place that results in the foreign cells being rejected by the body.