In 1956, Ivan Roitt demonstrated, jointly with Deborah Doniach, autoantibodies in clinical disorders of the thyroid gland. This discovery provided the first practical basis for autoimmunity as a cause of human disease and received the Van Meter and Gairdner awards. They subsequently identified autoantibodies characteristic of pernicious anaemia and primary biliary cirrhosis, developing methods for detecting autoantibodies still used in present day diagnostic procedures.

He classified autoimmune diseases in a spectrum from organ-specific to non-organ-specific with respect to autoantibody production. He introduced the C1q solid-phase assay for immune complexes, established the characteristics of ‘null cells’ responsible for the killing of antibody-coated target cells, and proposed the now standard nomenclature for B and T cells.

Ivan’s work provided strong evidence for IgG as the driving autoantigen in rheumatoid arthritis by analysis of synovial fluid complexes and extensive investigations of the carbohydrate changes in IgG and the mechanistic basis for this in patients and in close relatives. Ivan was Co-Founder of NALIA Systems, a biotechnology company based on novel economic analysis of multiple serum antibodies.