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Mary Sue Leffell, Ph.D.

Professor of Medicine



  • Professor
  • Director, Division of Immunognetics and Transplant Immunology
  • Director, Immunogenetics Laboratory
  • Professor of Medicine

Centers & Institutes


Contact for Research Inquiries

Phone: 410-955-3600

Research Interests

Transplantation Immunology; Immunogenetics


Dr. Mary S. Leffell is a Professor of Medicine and, along with Dr. Andrea A. Zachary, directs the Division of Immunogenetics and Transplant Immunology, Department of Medicine of the Johns Hopkins University School of Medicine. She holds a joint appointment in the Department of Molecular Microbiology and Immunology of the Johns Hopkins Bloomberg School of Public Health. Dr. Leffell has a Ph.D. in immunology from the University of North Carolina at Chapel Hill and is a Diplomate of both the American Board of Medical Laboratory Immunology (ABMLI) and the American Board of Histocompatibility and Immunogenetics(ABHI). She has over 30 years experience in clinical immunology, histocompatibility and immunogenetics. Previously, she has directed the Immunology Service Laboratory at the Eastern Virginia Medical School and the Histocompatibility and Immunogenetics Laboratories at Norfolk Sentara Hospital and the Medical College of Georgia.

Dr. Leffell is a past president of the American Society for Histocompatibility(ASHI) and Immunogenetics and has served two terms on the Board of Directors of the United Network for Organ Sharing (UNOS).From 2005-2009 she was a member of the Advisory Committee on Organ Transplantation to the Secretary of the Department of Health and Human Services. In 2011, she was honored with the Distinguished Scientist Award from the ASHI and in 2003, with a Distinguished Service Award. She is currently a member of the International Histocompatibility and Immunogenetics Council. She is also a member of the International Transplantation Society, the American Transplantation Society, The Association of American Imunologists, and the Association of Medical Laboratory Immunologists.

Dr. Leffell has published over 150 research articles, review articles and book chapters. She recently was co-editor of the second edition of Transplantation Immunology in the Methods in Molecular Immunology series. Her research interests have included population studies of the distribution of HLA alleles and haplotypes, minor histocompatibility antigens, KIR, and cytokine alleles among various racial/ethnic groups. Her studies in transplantation immunology have included the effect of proinflammatory events and infection on the breadth and strength of HLA-specific antibodies among sensitized solid organ transplant candidates; the incidence of post-transplant sensitization following mismatched allogeneic hematopoietic cell transplantation (HCT); desensitization and subsequent successful engraftment of HCT candidates with donor HLA-specific antibodies; and the incidence and impact of HLA-specific alloimmunization among patients requiring transfusion support.

Dr. Leffell has served on the American Board of Medical Laboratory Immunology and the American Board of Histocompatibility and Immunogenetics. She is a member of the editorial boards of Human Immunology and Transplantation and a previous member of the board of Clinical & Diagnostic Immunology.

Dr. Leffell is one of the founders and has served on the program committee and course faculty for the American Foundation for Donation and Transplantation (formerly the Southeastern Organ Procurement Foundation) Histocompatibility Specialist course since it was established in 1983. She has been a frequently invited speaker at international, national and regional meetings and educational workshops. more

    Additional Information

  • Education +

    Additional Training

    • Diplomate, American Board of Medical Laboratory Immunology (1979)
    • American Board of Immunogentics and Histocompatibility (1996)
  • Research & Publications +

    Technology Expertise: Histocompatibility, Molecular Genetics

  • Academic Affiliations & Courses +
  • Activities & Honors +


    • Phi Beta Kappa, 1967
    • Title IV NDEA Fellowship, 1968 - 1972
    • Torchbearer, University of Tennessee, 1968
    • Who's Who in American Colleges and Universities, 1968
    • Woodrow Wilson Fellow, 1968
    • Outstanding Young Women in America, 1975
    • Who's Who of American Women, 1991
    • Distinguished Service Award, American Society for Histocompatibility and Immunogenetics, 2003
    • Distinguished Scientist Award, American Society for Histocompatibility and Immunogenetics, 2011

    Professional Activities

    • Advisory Committee, Tissue and Gene Therapies Center for Biologics evaluation and Research 
      FDA Office of Cellular
    • Advisory Committee on Organ Transplanation to the Secretary, U.S. Department of Health and Human Services
    • Board of Directors, United Network for Organ Sharing 
    • Editorial Boards, Human Immunology
    • Editorial Boards, Clinical & Diagnostic Laboratory Immunology
    • Editorial Boards, Transplantation 
  • Videos & Media +
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