Antibodies aren’t the only immune cells needed to fight off COVID-19. T cells are equally important and can step up to do the job when antibodies are depleted, suggests a new Penn Medicine study of blood cancer patients with COVID-19 published in Nature Medicine.

For our comprehensive coverage and latest updates on COVID-19 click here.

The researchers found that blood cancer patients with COVID-19 who had higher CD8 T cells, many of whom had depleted antibodies from cancer treatments, were more than three times likelier to survive than patients with lower levels of CD8 T cells.

“It’s clear T cells are critical in terms of the early infection and to help control the virus, but we also showed that they can compensate for B cell and antibody responses, which blood cancer patients are likely missing because of the drugs”, says co-senior author Alexander C. Huang, an assistant professor of haematology-oncology in the Perelman School of Medicine and Penn’s Institute of Immunology. “This is important when we think about how to improve the care of cancer patients with COVID. We need to maximize all the arms of the immune system, especially if we know that one particular arm of the immune system is down”.

Additionally, because the current COVID-19 mRNA vaccinations induce both antibody and T cell responses, the findings suggest that vaccination of blood cancer patients could provide protection through T cell immunity, despite the absence of antibodies. The team—which includes researchers from Memorial Sloan Kettering Cancer Center—studied hospitalised patients with both solid tumours and hematologic cancers admitted to four Penn Medicine hospitals and Memorial Sloan Kettering to better understand the immune determinants of COVID-19 deaths.