Analysis of Humoral and Cellular Immunity of Lung Transplant Recipients Following SARS-CoV-2 Infection and BNT162b2 mRNA Vaccination

PURPOSE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in lung transplant recipients (LTxR) under immunosuppression carries higher risk with 14-39% mortality. Immune responses of LTxR under immunosuppression following SARS-CoV-2 infection or vaccination remains unknown. Our goal is to determine the humoral and cellular immunity to SARS-CoV-2 in LTxR with infection and following vaccination. METHODS: We performed a single center analysis to determine immune responses of LTxR with infection and following BNT162b2 mRNA vaccination. The results were compared with controls (non-transplant individuals). ELISA was developed to determine the antibody (Ab) concentration (IgG) to SARS-CoV-2 spike (CSP) and nucleocapsid (CNP) antigens. PBMCs from LTxR were isolated by ficoll-hypaque centrifugation to determining the frequency of cells secreting IFNγ and TNFα to CSP and CNP by ELISpot. RESULTS: Concentration of Abs developed and T-cell frequencies secreting TNFα and IFNγ against CSP and CNP in LTxR and controls are given in Table 1. Infected LTxR and controls developed Abs to both CSP and CNP. In contrast, vaccinated LTxR induced 10 fold less Abs to CSP in comparison to control. Frequencies of cells secreting TNFα for both CSP and CNP were significantly reduced in LTxR with infection. However, vaccination of both LTxR and control induced similar levels of TNFα secreting cells upon stimulation with both CSP and CNP. It is of interest that frequency of IFNγ producing cells against both CSP and CNP were significantly higher in LTxR in comparison to control. CONCLUSION: Infection with SARS-CoV-2 in LTxR and controls produced comparable levels of Abs both against CSP and CNP. However, vaccinated LTxR didn`t induce significant levels of Abs against CSP. Frequency of T-cells, secreting IFNγ were significantly increased by vaccination in LTxR and in controls suggesting that T cell responses against SARS-CoV-2 has been induced in LTxR by mRNA vaccine.