2008 Bill T. Teague Lectureship Summary - May 22, 2008
The 2008 Bill T. Teague Lectureship in Transfusion Medicine was held May 22 and featured guest lecturer Harvey G. Klein, MD. The lectureship, in its 12th year, honors contributions to the blood banking profession by Bill T. Teague, who served as president and CEO of Gulf Coast Regional Blood Center for 31 years.
Dr. Klein is Chief, Department of Transfusion Medicine, and has been Special Assistant to the Director for Science at the Clinical Center of the National Institutes of Health. He has authored or co-authored more than 200 publications pertaining to blood transfusion as well as co-authored the latest edition of Mollison's Blood Transfusion in Clinical Medicine, the acknowledged "gold standard" for textbooks in this discipline. Throughout his career, Dr. Klein has received numerous honors, including the NIH Clinical Center Director's Award, the AABB Emily Cooley Award, the Latham Award of the European Society of Hemapheresis, the Cohn-de Laval Award of the World Apheresis Association, and the John B. Alsever Award. Additionally, the Department of Health and Human Services (DHHS) has awarded Dr. Klein several awards, including the highest civilian award, the Secretary's Distinguished Service Award.
Dr. Klein began the lecture Pathogen Inactivation of Blood Components - the Consensus Conference and Beyond with a review indicating that the current blood supply in the U.S. is extraordinarily safe. Processes put in place to reduce the risk of transfusion-associated infectious diseases include careful donor history interview and examination, diversion pouch, donor testing, leukoreduction, component inspection, post donation information, donor deferral registries, limiting exposures and hemovigilance.
Even with current efforts, threats to the blood supply still exist, including the failure of the donor selection process, the absence of tests, insensitive tests, laboratory failure, and mutant or variant organisms. Dr. Klein classified the infectious threats to the blood safety into 1) Emerged: such as HBV, HCV, plasmodia, CMV; 2) Emerging: HIV, vCJD, SARS, bird flu; 3) Re-emerging: WNV, bacteria, T. cruzi, babesia; and 4) Submerging: HGV/GVB-C, TTV, SEN-V. The protective triads, donor screening and testing as well as pathogen inactivation (PI) all play a role in reducing the residual risk of infectious diseases. Dr. Klein traced the history of infectious diseases that are currently screened in the blood supply and reviewed those that are not included in the screening battery including SARS, Chikungunya virus, other vector-borne infections, Leishmania, malaria, vCJD, simian foamy virus, dengue, Ebola virus, and bacteria. Screening out all contaminated units would result in an inadequate blood supply. Risk assessments for all of these agents in all populations are an unachievable task.
Dr. Klein next moved into the new paradigm of PI and reviewed the Canadian Consensus Development Conference and the Advisory Committee on Blood Safety and Availability's recent recommendation to DHHS to set as a high priority, the urgent implementation of PI technology (PIT) to further reduce known and unknown infectious threats to the blood supply. The Consensus Development Conference was held March 2007 to discuss questions regarding PI. The risks of PI include damage to transfusion product, toxicity to recipient, processing personnel and environment. Benefits include reduction of known viruses, bacteria, parasites, and potential reduction of emerging and unknown pathogens.
Biopharmaceutical pathogen reduction/clearance technology includes pasteurization, fractionation, UV/propiolactone, low pH, AHF heat, solvent-detergent, affinity purification, nanofiltration, NAT testing, and finally, PIT. The current PIT, all of which are not yet approved by the FDA, include: 1) for single donor plasma: solvent detergent (SD, Octaplas) and methylene blue; and 2) for cellular components: psoralen (Amotosalen, S-59), riboflavin (Mirasol), and Helinx (S-303).
Dr. Klein summarized the lecture by stating that the blood supply in the U.S. and in other developed countries is extraordinarily safe and PIT could add an additional layer of safety, especially for window period infections and for emerging infections that recent history all but guarantees will occur. PIT have limitations including 1) a decreased component yield, 2) the PIT may also be insufficient to kill some small viruses and high-titer agents such as hepatitis A and Parvovirus B-19, 3) cost, and 4) toxicity. For a "tolerable" benefit-risk profile, PIT should offer broad inactivation spectrum, minimal damage to cells, little toxicity potential to the most vulnerable patients and a failsafe manufacturing system. PIT is no guarantee against the "next" virus or emerging pathogen. Geography, blood donor characteristics and the robustness of the health care delivery system may alter the benefit-risk calculus.
Dr. Klein's May 22, 2008 PowerPoint presentation can be viewed here.