Hydroxychloroquine Effects on TLR Signalling: Underexposed but Unneglectable in COVID-19

Figure 2

Immunosuppressive effects of HCQ. Hydroxychloroquine affects both the innate and adaptive immune system. By accumulating in the lysosome and autophagosome, the pH is increased causing an inhibition of MHC-II antigen presentation and subsequent T cell activation. In addition, HCQ accumulation abrogates viral recognition by endosomal TLRs, resulting in a decrease of the antiviral innate immune response (i.e., IFN-I production). Moreover, HCQ can also directly affect the adaptive immune system through inhibition of T and B cell differentiation and activation.