Cytotoxic lymphocyte-monocyte complex reflects the dynamics of COVID-19 systemic immune response.

SARS-CoV-2 infection causes a variety of clinical manifestations, many of which originate from altered immune responses, either locally or systemically. Immune cell crosstalk occurs mainly in lymphoid organs. However, systemic cell interaction specific to COVID-19 has not been well characterized. Here, by employing single cell RNA sequencing and imaging flow cytometry analysis, we unraveled, in peripheral blood, a heterogeneous group of cell complexes formed by the adherence of CD14+ monocytes to different cytotoxic lymphocytes, including SARS-CoV-2-specific CD8+ T cells, γδT and NKT cells. These lymphocytes attached to CD14+ monocytes that showing enhanced inflammasome activation and pyroptosis-induced cell death in progression stage, whereas in convalescent phase, CD14+ monocytes with elevated antigen presentation potential were targeted by cytotoxic lymphocytes, thereby restricting the excessive immune activation. Collectively, our study reports previously unrecognized cell-cell interplay in SARS-CoV-2 specific immune response, providing new insight into the intricacy of dynamic immune cell interaction representing anti-viral defense.