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Fellows Directory

Ian MacLennan

Ian MacLennan

Professor Ian MacLennan CBE FMedSci FRS


Elected: 2012


Ian MacLennan is an immunologist who has made important contributions to our understanding of immune responses, particularly in relation to antibody production and the physiology of white blood cells known as B cells. His early work led to the discovery of natural killer cells, blood cells that are important in protecting against cancer and viral infections.

Ian’s classic observations indicate that germinal centres are sites of affinity maturation for antibodies produced in response to infection or immunisation. This is achieved through clonal expansion of B cells and hypermutation of the genes that encode the antigen-combining sites of the antibodies they produce. These B cells are subsequently selected for their capacity to bind stored foreign antigens or deleted if they react against self.

His experiments also show that cells in the marginal zone of the spleen represent a distinct B-cell subset important in responses to bacterial surface polysaccharides. Ian founded the MRC Centre for Immune Regulation at the University of Birmingham, and was awarded a CBE in the Queen’s Birthday Honours list of 2005.

Interest and expertise

Subject groups

  • Microbiology, immunology and developmental biology
    • Cellular and humoral immunology
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