In contrast to COVID-19, which showed markedly elevated plasma concentrations of 11 SMs, we observed decreased levels of several SMs, mainly pro-inflammatory cytokines (e.g., IFN-γ, IFN-α2, TNF-α, IL-7, IL-17A, and IL-15) in both the remission and acute phases of TTP. Here, IL15 is linked to thrombotic thrombocytopenic purpura.