ABSTRACT
Purpose: To evaluate post-vaccination cellular and antibody (Ab) immunity after COVID-19 vaccination in single blood samples from 17 kidney transplant (KT) recipients who had received COVID-19 vaccination Methods: We measured frequencies of peripheral blood T- and B-cells which expressed the inflammatory marker CD154 after overnight stimulation with peptide mixtures representing the spike protein S, its S2 component which is conserved between SARS-CoV-2 and human coronaviruses, and the S1 component, which is specific to SARS-CoV-2 and also contains its receptor binding domain (RBD). Serum from each sample was assayed for anti-RBD and anti-S IgG Abs with ELISA. Optical density at 450nm (OD450) of 0.45 or greater implied presence of either Ab. Frequencies of monocytic and polymorphonuclear (PMN) myeloid-derived suppressor cell were also measured with flow cytometry. Result(s): Median age was 40 yrs (range 25 to 83), male:female gender distribution was 7:8. All recipients received mRNA vaccination. Anti-S-IgG and anti-RBD-IgG were detected in 11 (Ab+) and were absent in four (Ab-). Compared with Ab+ KT recipients, those who were Ab- had lower frequencies of S2-reactive and S-reactive B-cells (p<0.05), CD4+ and CD8+ T-cells (Table 1, Fig 1). S1-reactive T-cell and B-cells were non-detectable. Frequencies of PMN-MDSC were numerically higher in Ab- compared with Ab+ KT recipients (Mean +/- SEM 38.9+/-8.1 vs 19.4+/-1.8, p-value 0.1, NS). Significant negative correlation was observed between PMN-MDSC frequencies and strength of anti-RBD IgG and anti-SPIKE IgG (Fig 1). Conclusion(s): COVID-19 vaccination results in spike antigen reactive T- and B-cells in KT recipients who develop Abs after vaccination. Failure of an Ab response is associated with impaired B-cell responses to the spike antigen and an increase in circulating polymorphonuclear myeloid derived suppressor cells. (Table Presented).
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.
ABSTRACT
Purpose: Chronic immunosuppression can impair antibody responses after natural infection and vaccination in SOT recipients. It is not known whether antibody responses are impaired in SOT compared with non-SOT patients with COVID-19 Methods: We evaluated IgG responses to the spike (S) and receptor binding domain (RBD) antigenic sequences of SARS-CoV-2 after COVID-19-infection in SOT and non-SOT patients using enzyme-linked immunosorbent assay (ELISA). The S protein consists of a conserved C-terminal and less conserved N-terminal S1 sequence which contains the RBD. An optical density (OD) at 490 nm of 0.45 or greater, or < 0.45 was read as positive and negative ELISA result based on pre-clinical validation in 148 subjects. S1-reactive, S2-reactive and S-reactive CD4 cells that expressed CD154 were measured with flow cytometry after overnight stimulation with respective peptide mixtures for these antigens. Results: 204 total study subjects, mean+/-SD age 47.5+/-21 years, were sampled at mean 12.6 (range 0-94) days after diagnosis. Subjects included 107 males, 74 SOT (liver-48, kidney-26) and 130 non-SOT. Among them, 103 patients with COVID-19 included 32 SOT and 71 non-SOT. Antibody measurements were performed in 74 COVID-19 patients. Fifty one of 74 patients received convalescent plasma. Anti-spike and anti-RBD IgG were present in 49 of 51 (96%) and 47 of 51 (92%) patients, respectively. Among the remaining 23 patients who did not receive plasma, anti-spike IgG and anti-RBD IgG were present in 21 (91%) and 16 (69.5%) patients, respectively. The incidence of anti-RBD IgG was significantly lower in SOT, 2 of 7 or 29%, compared with non-transplant patients, 14 of 16 or 88% (p=0.011). Betweengroup differences in the incidence of anti-spike IgG were not significant (5/7 or 71% SOT vs 16/16 or 100% SOT, p=NS). One of 23 patients, an SOT recipient died and showed no IgG to S or RBD antigens. Antibody titers reflected in OD490 readings were lower in SOT compared with non-SOT for anti-spike IgG (mean 2.2+/-0.6 vs 1.4+/-1.2, p=0.16, NS) and anti-RBD IgG (1.8+/-0.9 vs 0.54+/-0.7, p=0.004). Subjects without and with anti-RBD antibody did not differ in timing of the sample from diagnosis (mean+/-SD 18+/-12.5 vs 12+/-12, p=0.258, NS, respectively), frequencies of S-, S1 or S2-reactive T-cells (mean 3.1+/-2.4% vs 1.8+/2%, p=0.225, NS, respectively), or proportions of patients requiring intubation (2/7 or 29% vs 4/16 or 25%, p=1.00, NS, respectively). Conclusions: Chronically immunosuppressed liver and kidney transplant recipients demonstrated impaired antibody responses to SARS-CoV-2 spike antigens, especially to less conserved RBD-containing viral sequence. This finding may portend impaired vaccine efficacy in transplant recipients.