It was previously shown that the addition of IL-6 in the growth medium of healthy dendritic cells attenuated HLA-DR membrane expression and decreased the production of IFN-γ by CD4 cells (Ohno et al., 2016). Three findings of our study are compatible with the proposal that IL-6 is one of the drivers of decreased HLA-DR on the CD14 monocytes: (1) IL-6 concentrations in the blood is inversely associated with HLA-DR expression (Figure 5A), (2) the addition of Tocilizumab in the plasma-enriched medium of cells partially restored the expression of HLA-DR on cell membranes (Figures 5E and 5F), and (3) absolute lymphocyte counts of six patients increased after Tocilizumab treatment (Figure 5G). Our findings are indirectly supported by the increase of circulating HLA-DR+ cells during convalescence of one case of COVID-19 of moderate severity (Thevarajan et al., 2020).