Development of T-cell immunity in a liver and hematopoietic stem cell transplant recipient following coronavirus disease 2019 infection

The outbreak of coronavirus disease 2019 (COVID-19) has disproportionately affected patients with comorbidities, including recipients of solid organ and hematopoietic stem cell transplants (SCT). Upon recovery from COVID-19, the degree of the immunological protection from reinfection remains unclear. Here we describe a 33-year-old patient with erythropoietic protoporphyria (EPP) who had undergone liver transplantation with splenectomy followed by allogeneic SCT in 2013 after an initial failed liver and umbilical cord transplant. The patient developed mild upper respiratory symptoms in the spring of 2020 and was found to have anti-SARS-CoV2 antibodies suggesting past infection. A comprehensive analysis of T cell functionality in peripheral blood from this patient revealed robust in vitro responses against SARS CoV2 antigens Spike (S) 1 and 2, membrane (M) and nucleoprotein (NP), comparable to the reactivity against common antigens from CMV, EBV, Ad and BK viruses, while only low reactivity was seen in healthy donors without documented history of COVID-19. Moreover, the patient displayed a marked recognition of counterpart antigens from related human coronaviruses (hCoVs) 229E, OC43, NL63 and HKU1. Thus, despite lifelong immunosuppression, this survivor of COVID-19 retained a remarkable degree of immunocompetence and showed broad-spectrum T cell memory specific for SARS-CoV2 and related hCoVs including less studied hCoV M and NP antigens. The study highlights the role of cellular immunity after natural COVID-19 infection, suggesting broader use of T cell assays as a tool for risk stratification, measurement of immunocompetence and/or post-infection or post-vaccination protection, and possible T cell-based adoptive immunotherapy strategies in high-risk patients.