Fig 2: COVID-19 patients with higher levels of Tregs and Bregs in the PBMCs have lower levels of proinflammatory cytokines in the plasma. (A–E) Correlation between levels of IL-35 and IL-10 producing CD138+ CD1d+ Bregs and serum markers of COVID-19 severity such as CRP, D-Dimer, ferritin, and proinflammatory cytokines such as IL-6, IL-17, TNFα, and IL-1β. (F,G) Correlation between levels of cTreg and IL-6 and IL-1β. (H–J) Correlation between levels of LAG3 cTreg/uTreg and IL-17 and TNFα. Statistical test: Pearson’s correlation or Spearman’s coefficient was used based on the normality of data, with a two-sided test for significance (P < 0.05, considered significant).

Fig 3: Levels of regulatory B cells in the PBMCs of patients with COVID-19 with COVID-19 with and without auto-Abs to type I IFNs. (A,B) Levels of IL-35 and IL-10 producing CD138+ CD1d+ Bregs in the PBMCs of patients with severe COVID-19, both with and without auto-Abs to type I IFNs, and those who were non-hospitalized. (C–F) Levels of IL-10 and IL-35 in plasma of patients with severe COVID-19, both with and without auto-Abs to type I IFNs, and those who were non-hospitalized. Events were recorded and analysed by using BD FACSDiva version 8.0. Statistical tests; Comparison between patients with and without auto-Abs to type I IFNs was performed using unpaired t-test or Mann–Whitney U test, depending on the skewness of the data. Linear regression models adjusted for patient’s age and DM was utilized for other analysis. P value of < 0.05 was considered significant.