In a publication in the Journal of Clinical Investigation, Drs. Daniel Kaufmann and Andrés Finzi from Université de Montréal and collaborators, found that patients with acute SARS-CoV-2 infection have altered immune responses affecting the severity of symptoms and mortality. These findings may help clinicians identify patients at risk of unfavourable outcomes and shed light on what new therapies could seek to target. This study was funded in part by the COVID-19 Immunity Task Force, in collaboration with the Canadian Institutes of Health Research (CIHR).


Two groups of patients, comparable in age and sex, were recruited from a large hospital to determine the differences in immune cell responses between SARS-CoV-2 patients and other patients with acute diseases. A third group of healthy controls was included. These patients had blood samples collected at several time points and analysis by flow cytometry was done to identify different types of cells in the blood samples. Researchers found specific differences between SARS-CoV-2-infected and uninfected individuals when it came to two distinct types of immune cells involved in defending the body from infection (myeloid and lymphoid cells). Among the changes found were high levels of CD38+CD8+ T cells in patients with severe COVID-19, which was also found to be associated with mortality. The research team found other specific markers that could indicate the degree of severity: PD-1 on CD4+ T cells, and ICAM-1 and ALCAM on neutrophils and antigen presenting cells (B cells, monocytes). They suggest these should be further studied as potential therapeutic targets.

Researchers concluded that the technique used in this study can easily be deployed in other clinical settings and used to complement patient follow-ups, as well as aiding clinicians in identifying patients at risk of unfavourable outcomes.


Rébillard RM, Charabati M, Grasmuck C, Filali-Mouhim A, Tastet O, Brassard N, Daigneault A, Bourbonnière L, Anand SP, Balthazard R, Beaudoin-Bussières G, Gasser R, Benlarbi M, Carmena Moratalla A, Carpentier Solorio Y, Boutin M, Farzam-Kia N, Descôteaux-Dinelle J, Fournier AP, Gowing EM, Laumaea A, Jamann H, Lahav B, Goyette G, Lemaître F, Mamane VH, Prévost J, Richard J, Thai K, Cailhier JF, Chomont N, Finzi A, Chassé M, Durand M, Arbour N, Kaufmann DE, Prat A, Larochelle C. Identification of SARS-CoV-2-specific immune alterations in acutely ill patients. J Clin Invest. 2021 Apr 15:145853. doi: 10.1172/JCI145853