Since the start of the COVID-19 pandemic, researchers have been trying to figure out why someone develops a mild or severe case. One way to do that is by looking at T cells, which are white blood cells that mount an immune response—and specifically CD8+ T cells, “killer” T cells that have been shown to effectively fight back against COVID-19 infections.
But most studies examining what leads to different COVID-19 immune responses have not taken differences between individual immune systems into consideration.
Moriya Tsuji, a professor at the Texas A&M University School of Engineering Medicine, said one important factor is a group of genes called human leukocyte antigens (HLAs). These genes help determine how the immune system recognizes pieces of a virus and activates T cells, and different people carry different HLA types.