Researchers at the University of Pennsylvania, US, 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 more likely 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," said Alexander C. Huang, Assistant Professor of Hematology-Oncology at the varsity's Perelman School of Medicine.

"This is important when we think about how to improve the care of cancer patients with Covid. We need to maximise all the arms of the immune system, especially if we know that one particular arm of the immune system is down," Huang added.

Additionally, because the current Covid-19 mRNA vaccinations induce both antibody and T cell responses, the findings, published in Nature Medicine, suggest that vaccination of blood cancer patients could provide protection through T cell immunity, despite the absence of antibodies.

The team found that patients with blood cancer were more likely to die from Covid-19 than patients with solid tumours or without cancer.

Further, immune profiling of 214 patient blood samples revealed that patients with blood cancers, in particular patients treated with anti-CD20 antibodies, had decreased B cells and antibodies compared to patients with solid cancers and patients without cancer.

Additional analyses also revealed that among patients with blood cancers, including patients treated with chemotherapy and anti-CD20 antibodies, those with higher CD8 T cell counts had a 3.6 fold greater likelihood of survival compared to those with lower counts.

Thus, the researchers concluded, CD8 T cells may influence recovery from Covid-19 when B cells and antibodies are deficient.