Hospitalized SARS-CoV-2 patients had a persistent decline in CD4+ T cells, whereas CD8+ T cells gradually recover after one month
To assess the longitudinal effect of COVID-19 on T cell populations, we sampled PBMCs from patients with COVID-19 over a period of 6-8 months. PBMCs were analyzed by flow cytometry to investigate immunophenotype across the various T cell compartments.
The lymphocyte populations recovered, with a substantial increase in cell counts at 1 month (P=0.0003) that remained consistent until 6-8 month (P=0.0003) (Figure 1A). Total T cells (CD3+T cells) increased significantly after one month (P0.0001) and then dropped slightly at 6-8 months (P=0.022) but remained significantly higher than at the time of enrolment (P=0.021) (Figure 1B) (Table 3).
When comparing CD4+T cells to enrolment, a constant and significant reduction was observed at one month (P=0.022) and continued until 6-8 months (P=0.0016) (Figure 1C). In relation to CD8+ T cells, the increase was significantly higher at 6 months compared to that at enrolment (P=0.017) and at one month (P=0.012) (Figure 1D) (Table 3).
Together, these data are reflective of the alterations in the levels of various immune cell types during COVID-19, in line with observations made by others [5-9].