ABSTRACT
Purpose: We describe the clinical presentation & immune response to COVID-19 infection in pediatric SOT. Methods: Medical records of COVID-19 PCR+ or seropositive patients were reviewed for details of their disease course. Blood was obtained during PCR or seropositivity for immunophenotyping & PlexCOVID-19 test. PlexCOVID-19 measures frequencies of spike Ag reactive T cells that express CD154. A preestablished algorithm predicts likelihood of COVID-19 severity. Controls were peds SOT patients with negative COVID-19 status. RNA isolated from liver tissue for PCR using the Lyra SARS CoV-2 Assay. As induction of immunological memory is central to anti-pathogen adaptive immunity induced by infection, IHC of liver tissue for tissue resident memory cells (TRM) (defined as CD69+ expressing CD4 or CD8 T cells) was performed. Results: 4 patients had COVID-19 & 5 patients were seropositive between March & Nov 2020 (Table 1). The 2 symptomatic PCR+ patients were hospitalized for 24-48-hours & the symptomatic seropositive patient had a prolonged PICU stay. Steroid was discontinued in 1 symptomatic PCR+ patient;& target CNI goal & steroid dose decreased in the symptomatic seropositive patient due to concurrent BK viremia. 8 patients remain well at home. Histology on 1 symptomatic PCR+ patient with elevated LFT's revealed lymphocytic portal inflammation & SARS CoV-2 PCR on the liver was negative;histology on 1 asymptomatic seropositive patient was normal. Infrequent TRM were seen on liver biopsies but were increased in PCR+ & seropositive biopsies vs. biopsies from same patients that pre-date a COVID-19+ status. CD4+ T cells in PCR+ & seropositive patients had a phenotype consistent with activation, including expression of HLA-DR (p = 0.008);Further, BST2 was constitutively expressed on a subset of CD4+ T cells in PCR+ patients reflecting a history of IFN-alpha induced signals (p=0.01). The frequencies of spike Ag-reactive CD3 (0.95 ± 0.35 vs 2.73 ± 0.35, p= 0.037) and CD8 cells (1.10 ± 0.70 vs 5.03 ± 0.80, p= 0.034) were lower in symptomatic PCR+ patients compared with asymptomatic seropositive subjects. Conclusions: A small number of our SOT patients had mild or asymptomatic COVID-19 infection, with notable activation of CD4+ T cells, & constitutive expression of BST2 reflecting IFN-alpha induced signals. Spike-antigen-reactive T-cells was lower during symptomatic vs. asymptomatic infection.
ABSTRACT
Purpose: We assessed whether COVID-19-risk is enhanced by chronic immunosuppression, and is associated with suppressor cells. Methods: We tested 66 COVID-19 patients, including 26 with solid organ transplants at median 11 days after diagnosis, and 64 unexposed healthy subjects including 21 with transplants, who were sampled pre-pandemic. T- and B-cells, which express CD154 were measured after stimulation with peptide mixtures representing the spike protein S, its conserved C-terminal S2, and less conserved N-terminal S1 components. Monocytic myeloid-derived suppressor cells (M-MDSC) were measured in an independent cohort of 47 COVID-19 patients Results: Frequencies (%) of S-reactive T-cells (Mean±SEM 2.0±0.3 vs 3.8±0.3, p=5.6E-05) and B-cells (3.0±0.4 vs 5.1±0.4, p=0.0003) were significantly lower in COVID-19 compared with healthy subjects, but were measurable in all samples. Transplanted and non-transplanted subjects demonstrated similar within group frequencies of S-reactive T-cells (4.1±0.3 vs 3.7±0.5, p=NS in healthy and 1.5±0.4 vs 2.4±0.3, p=NS in the COVID-19 group) and other S-reactive cells. Among COVID-19 patients, intubated patients showed lower S-reactive CD8 frequencies compared with non-intubated patients. (1.4±0.5 vs 3.5±0.5, p=0.003). In logistic regression analysis using training and test sets, S-reactive CD3 and CD8 cells, age, race, and transplantation status distinguished COVID-19 from healthy subjects (test set negative and positive predictive values 75% and 85% respectively, AUC 0.9). Among 66 COVID-19 patients, S-reactive CD8 cells and age predicted respiratory failure with NPV 62%, PPV 86%, AUC 0.73. S2-reactive T-cells demonstrated similar predictive performance. S1 antigen elicited minimal cellular responses. Transplanted COVID-19 patients show lower cytomegalovirus-specific CD154+CD3 frequencies compared with non-transplanted patients (0.5±0.1 vs 1.3±0.2, p=0.006). Frequencies of CD14+CD33+CD11b+HLADR-ve M-MDSC (14.5±2.9 vs 3.3±1.5, p=0.002) were higher in 47 independent COVID-19 patients compared with 6 healthy subjects. Conclusions: Conserved SARS-CoV-2-spike antigen drives T-cell immunity to COVID-19 in unexposed transplanted and non-transplanted subjects. This immunity declines with COVID-19 infection, is accompanied by increased myeloid derived suppressor cells, and can predict infection-risk and disease severity. Transplant patients demonstrate increased COVID-19-risk and co-infection-risk.