Landsteiner Karl (1868, Baden - 1943, New York), Austrian bacteriologist and immunologist, Nobel Prize in Medicine (1930), founder of immunohematology and immunochemistry. In 1900, he proposed the hypothesis that agglutination after the administration of foreign blood plasma to a person is caused by agglutinins and special receptors located on the surface of blood cells.

Experimental confirmation of this hypothesis allowed Landsteiner to explain the "Wasserman reaction" and to discover the possibility of transforming proteins in the body into autoantigens under the influence of foreign non-protein bodies. The existence of people of different blood groups, which was established, revolutionized hematology and made it possible to widely use blood transfusions.