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Archive - Oct 19, 2020

Older, Male Patients Who Had More Severe COVID-19 May Be Best Donors for Convalescent Plasma Therapy

Sex, age, and severity of disease may be useful in identifying COVID-19 survivors who are likely to have high levels of antibodies that can protect against the disease, according to a new study co-led by researchers at the Johns Hopkins Bloomberg School of Public Health. The findings suggest that older males who have recovered from COVID-19 after having been hospitalized are strong candidates for donating plasma for treating COVID-19 patients. Doctors have been using infusions of plasma--the part of blood that contains antibodies--from recovered COVID-19 patients to treat COVID-19 patients and also as a possible prophylaxis to prevent COVID-19. Doctors have used convalescent plasma to treat patients or immunize persons at high risk of virus exposure during outbreaks of measles, mumps, polio, Ebola, and even the 1918 pandemic flu. Clinical trials of convalescent plasma treatment against COVID-19 are ongoing, and doctors until now haven't had guidance for selecting COVID-19 survivors who are likeliest to have strong antibody responses. "We propose that sex, age, and severity of disease should be used to guide the selection of donors for convalescent plasma transfer studies because we found that these were significant patient characteristics that not only predicted the amount of antibody but the quality of that antibody," says study lead author Sabra Klein, PhD, Professor in the Bloomberg School's Department of Molecular Microbiology and Immunology.

Natural Killer (NK) Cells Also Have a Memory Function; Study Shows One Third of NK Cells in Liver Have Antigen Specificity; These Antigen-Specific NK Cells Also Exhibit Unique Gene Expression Profile

Researchers from MedUni Vienna's Departments of Dermatology and Surgery in Austria have managed to ascribe an immunological memory function to a subset of cytotoxic natural killer (NK) cells, which have hitherto been regarded as antigen-non-specific. The researchers found, under the leadership of Georg Stary, MD, PhD, who is also Co-Director of the Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases and affiliated with the CeMM (Research Center for Molecular Medicine of the Austrian Academy of Sciences), that approximately one third of all human liver NK cells can remember viruses and therefore respond specifically to them. These cells are therefore an interesting target for prophylactic use in the human immune system in the fight against infections and viruses. NK cells are natural cytotoxic killer cells in human blood and are a type of lymphocyte, a subgroup of white blood cells or leukocytes. They are able to identify and kill abnormal cells such as tumor cells or virally infected cells (apoptosis). Up until now, NK cells have been regarded as having no memory function, meaning that they are unable to kill on an "antigen-specific" basis but are only able to react afresh each time to viruses and sources of infection in a non-specific way. In the new study, published online on October 2, 2020 in Science Immunology, the MedUni Vienna scientists reported that that there is a subset of NK cells in the liver--the organ which is generally regarded as a large reservoir for NK cells--that is able to fight infections such as hepatitis A and B and to remember them. This subset also exhibits a unique gene expression profile that is different from that of other NK cell groups. The Science Immunology article is titled “A Discrete Subset of Epigenetically Primed Human NK Cells Mediates Antigen-Specific Immune Responses.”