Sydney Cohen made a series of important contributions to the understanding of immunity. Commencing with metabolic studies, he provided the first quantitative data on the distribution and turnover of IgC and IgM in humans. Turning to structural studies, he showed that the light chains were common to all classes of immunoglobulin but that light chains of the normal proteins were heterogeneous in contrast to those of monoclonal proteins.
Perhaps of greatest significance was his work with malaria. Sydney (with Ian McGregor) showed for the first time, that immunity could be passively transferred with immune IgG. An in vitro assay was devised for analysing the mechanism of malaria immunity and the variant specificity of protective antibody was demonstrated. This provided a means of isolating malarial antigens and free merozoites and for analysing the basis of host specificity. A practical method has resulted for screening antimalarial drugs.
Professor Sydney Cohen CBE FRS died on 24 June 2017.
