Evidence of potent humoral immune activity in COVID-19-infected kidney transplant recipients

Abstract

Whether kidney transplant recipients are capable of mounting an effective anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) adaptive immune response despite chronic immunosuppression is unknown and has important implications for therapy. Herein, we analyzed peripheral blood cell surface and intracellular cytokine phenotyping by flow cytometry along with serum antibody testing in 18 kidney transplant recipients with active coronavirus disease 2019 (COVID-19) infection and 36 matched, transplanted controls without COVID-19. We observed significantly fewer total lymphocytes and fewer circulating memory CD4⁺ and CD8⁺ T cells in the COVID-19 subjects. We also showed fewer anergic and senescent CD8⁺ T cells in COVID-19 individuals, but no differences in exhausted CD8⁺ T cells, nor in any of these CD4⁺ T cell subsets between groups. We also observed greater frequencies of activated B cells in the COVID-19 patients. Sixteen of 18 COVID-19 subjects tested for anti-SARS-CoV-2 serum antibodies showed positive immunoglobulin M or immunoglobulin G titers. Additional analyses showed no significant correlation among immune phenotypes and degrees of COVID-19 disease severity. Our findings indicate that immunosuppressed kidney transplant recipients admitted to the hospital with acute COVID-19 infection can mount SARS-CoV-2-reactive adaptive immune responses. The findings raise the possibility that empiric reductions in immunosuppressive therapy for all kidney transplant recipients with active COVID-19 may not be required.

Keywords: immune regulation; immunobiology; immunosuppressant - other; immunosuppression/immune modulation; infection and infectious agents - viral; kidney transplantation/nephrology; translational research/science.

FIGURE 1

Total lymphocytes and T cells in coronavirus disease 2019 (COVID-19) transplant patients and in COVID-19 negative controls. A,B, Total lymphocytes and CD3⁺ percentage of acquired cells. C, D, CD4⁺ and CD8⁺ cells percentage of CD3⁺ and E, calculated CD4⁺/CD8⁺ ratio. For 20 control patients, lymphocyte and total T cell absolute numbers were not available. Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05; **P < .01; ***P < .001. CTR, controls [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 2

CD4⁺ T cells and cytokines in coronavirus disease 2019 (COVID-19) transplant patients and in COVID-19 negative controls. A-C, Naïve, effector, and memory CD4⁺ cells percentage of total CD4⁺ T cells. D,E, Regulatory T cells (T_REG) and activated T_REG percentage of CD4⁺. F-H, Dysfunctional CD4⁺ T cell percentages of total CD4⁺ T cells. We did not have enough cells to perform naïve, effector, memory, and T_REG staining for 6 COVID-19 patients. For 17 control patients, staining was not done for exhaustion, anergic, or senescent cells. Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05; ** P < .01; ***P < .001. CTR, controls; T_REG, regulatory T cells [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 3

CD8⁺ T cells in coronavirus disease 2019 (COVID-19) transplant patients and in COVID-19 negative controls. A-C, Naïve, effector, and memory CD8⁺ cells percentage of total CD8⁺ T cells. We did not have enough cells to perform staining for 6 COVID-19 patients. D-F, Dysfunctional CD8⁺ cells percentage of total CD8⁺ T cells. For 17 control patients, staining was not done for exhaustion, anergic, or senescent cells. Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05; ** P < .01; ***P < .001. CTR, controls [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 4

T_FH and B cells subsets and anti-SARS-CoV-2 IgG and IgM antibody levels in coronavirus disease 2019 (COVID-19) transplant patients and in COVID-19 negative controls. A-D, Total T_FH and T_FH subsets percentage of CD4⁺; E-J, B cell subsets that differ significantly between groups. We did not have enough cells to perform T_FH staining for 6 COVID-19 patients. For 2 control patients, staining was not done for Total T_FH and T_FH subsets. Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05; **P < .01; ***P < .001. K, Anti-SARS-CoV-2 IgM and L, IgG at various time-points after symptoms onset. Each dot represents an individual value. Dotted line represents optical density (OD) ratio to negative control. *P < .05. CTR, controls; IgG, immunoglobulin G; IgM, immunoglobulin M; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; T_FH, follicular helper T cell [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 5

Cell subsets and anti-SARS-CoV-2 antibody levels according to coronavirus disease 2019 (COVID-19) severity. T and B cell subsets and anti-SARS-CoV-2 IgM and IgG levels in COVID-19 patients stratified in 3 groups according to disease severity at the time of sampling: 3 to 4, low (n = 7); 5, moderate (n = 6); and 6 to 7, severe (n = 5) . We defined COVID-19 severity using a scale from 1 (not hospitalized and resumed normal activities) to 7 (death). Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05. Average of control samples is shown by dotted horizontal line on bar charts. No subsets are significantly different between groups. IgG, immunoglobulin G; IgM, immunoglobulin M; IL, interleukin; IFN-γ, interferon γ; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TNFα, tumor necrosis factor α [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 6

Serial cell subsets and anti-SARS-CoV-2 antibody levels in 3 coronavirus disease 2019 (COVID-19) patients. T and B cell subsets and anti-SARS-CoV-2 IgM and IgG levels at 2 serial time points in 3 COVID-19 patients. Patients COVIDTX12 and COVIDTX28 were discharged at 47 and 45 d since symptom onset, respectively, while patient COVIDTX32 died on day 32. IgG, immunoglobulin G; IgM, immunoglobulin M; IL, interleukin; IFN-γ, interferon γ; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; TNFα, tumor necrosis factor α; T_REG, regulatory T cells [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 7

Cell subsets in coronavirus disease 2019 (COVID-19) positive nontransplanted individual and in healthy controls. Time-of-flight mass cytometry (CyTOF) analyses of T and B cell subsets in COVID-19 patients stratified in positive nontransplanted individuals and in healthy controls. Data are represented as mean and standard error of the mean (SEM). Each dot represents an individual value. *P < .05. IgM, immunoglobulin M; T_REG, regulatory T cells [Color figure can be viewed at wileyonlinelibrary.com]