Sustained expression of inflammatory monocytes and activated T cells in COVID-19 patients and recovered convalescent plasma donors

Trehanpati, N.; Singh, R.; Bajpai, M.; Yadav, P.; Maheshwari, A.; Kumar, S.; Agrawal, S.; Kumar, J.; Islam, M.; Maras, J. S.; Ramakrishna, G.; Sarin, S. K.

Intense monocyte activation and infiltration into the target tissues is the main mechanism of lung injury in SARS CoV2 infection. A reduction in the degree and nature of such cellular responses is expected following recovery. We aimed to investigate the immune responses in severe Covid-19 patients and recovered patients. Methods: Severe COVID-19 patients (n=34) at Lok Nayak Hospital, New Delhi and COVID-19 recovered patients (n=15) from mild disease and considered for convalescent plasma (COPLA) donation at Institute of Liver and Biliary Sciences (ILBS), New Delhi were recruited. We performed a multiplex cytokine bead assay in plasma and detailed multicolour flow cytometric analysis in peripheral blood of both groups and outcomes were compared in both groups and with healthy controls (n=10). Results: A significant increase in inflammatory markers [MIP1-a, MIP3a, MCP1, MIF, MMP12, ITAC, VEGF-A, and leptin] was observed in severe patients. Non-survivors additionally showed increased IL-6 levels. Despite the sustained expression of MIPs, the recovered patients showed a surge in MCSF and IL-18 levels. Both the groups had increased CCR2, CX3CR1 positive monocytes, low CD8 T cells, APRIL and BAFFR+ve B cells compared with healthy subjects. In conclusion, patients who have recovered and considered for COPLA donations still have compromised immunity with sustained expression of inflammatory monocytes and activated T cells.