Cellular and humoral immune responses after SARS-CoV-2 vaccination in pediatric kidney recipients

Objective: Humoral and cellular immune responses to SARS-CoV-2 vaccination are reduced in adult kidney recipients. After pediatric kidney transplantation there are only few data available - mostly limited to monitoring of SARS-CoV-2 antibodies. Method(s): Cellular and humoral immune responses have been monitored before and after SARS-CoV-2 vaccination in pediatric kidney recipients. After in vitro stimulation with SARS-CoV-2 antigen (spike glycoprotein) virus-specific CD4 and CD8 T cells (SARS-CoV-2-Tvis) have been identified by cytokine flow cytometry. SARS-CoV-2 IgG was measured by CMIA. Result(s): Immune response after SARS-CoV-2 vaccination was analyzed in a total of 30 pediatric kidney recipients (age at 1st vaccine dose 5.2 - 17.8 years, median 14.8 years;43% male;30/30 2 vaccine doses;23/30 3 vaccine doses). At time of vaccination 22 patients (73%) received a tacrolimus (Tac)-based immunosuppression combined with mycophenolate mofetil (MMF;n = 15) or everolimus (n = 6) or neither of them (n = 1);3 patients were exposed to cyclosporine A and 5 patients to a calcineurin inhibitor (CNI)- free immunosuppression. MMF was used in 18/30 patients. After 1st dose of mRNA vaccine SARS-CoV-2 antibodies were detectable in 50% of pediatric kidney recipients, after 2nd dose in 78% and after 3rd dose in 88%. After the 2nd vaccine dose absence of humoral immune response (< 33.8 BAU/ml) was only found in case of MMF use (predominately combined with Tac). Peak IgG values (> 2,080 BAU/ml) were only detected in MMF-free regimens (6/7). Cellmediated response partially differed from humoral response, e. g., in some patients SARS-CoV2-Tvis were found despite lack of virus-specific antibodies. After 1st vaccine dose SARS-CoV-2-Tvis were detectable in 50% of pediatric kidney recipients, after 2nd dose in 92%. After 2nd vaccine dose absence or very low levels of SARS-CoV-2-Tvis (< 0.3 cells/mul) were only found in Tac-based immunosuppressive regimens, whereas higher levels (> 1.3 cells/mul) were exclusively detected in patients with MMFfree medication. Conclusion(s): After pediatric kidney transplantation humoral and cellular immune responses to SARS-CoV-2 vaccination were suboptimal, but more pronounced than in adult kidney recipients. Use of Tac and MMF was associated with impaired immune response to vaccination. SARS-CoV-2-specific humoral response corresponded only partially to cell-mediated response. Additional monitoring of SARS-CoV- 2-Tvis might be recommendable to improve assessment of the individual vaccine response and thereby to personalize the decision on the necessity of further vaccine doses.

Characterization of SARS-CoV-2-Specific Humoral and Cellular Immune Responses Induced by Inactivated COVID-19 Vaccines in a Real-World Setting

While the immunogenicity of inactivated vaccines against coronavirus disease 2019 (COVID-19) has been characterized in several well-conducted clinical trials, real-world evidence concerning immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) raised by such vaccines is currently missing. Here, we comprehensively characterized various parameters of SARS-CoV-2-specific cellular and humoral immune responses induced by inactivated COVID-19 vaccines in 126 individuals under real-world conditions. After two doses of vaccination, S-receptor binding domain IgG (S-RBD IgG) and neutralizing antibody (NAb) were detected in 87.06% (74/85) and 78.82% (67/85) of individuals, respectively. Female participants developed higher concentrations of S-RBD IgG and NAb compared to male vaccinees. Interestingly, a longer dosing interval between the first and second vaccination resulted in a better long-term SARS-CoV-2 S-RBD IgG response. The frequencies of CD4+ T cells that produce effector cytokines (IFN-gamma, IL-2, and TNF-alpha) in response to stimulation with peptide pools corresponding to the SARS-CoV-2 spike (S), nucleocapsid (N) or membrane (M) protein were significantly higher in individuals received two doses of vaccine than those received one dose of vaccine and unvaccinated individuals. S, N, or M-specific CD4+ and CD8+ T cell responses were detectable in 95.83% (69/72) and 54.16% (39/72) of double-vaccinated individuals, respectively. The longitudinal analysis demonstrated that CD4+ T cell responses recognizing S, N, and M waned quickly after a single vaccine dose, but were boosted and became more sustained following a second dose. Overall, we provide a comprehensive characterization of immune responses induced by inactivated COVID-19 vaccines in real-world settings, suggesting that both humoral and cellular SARS-CoV-2 specific immunity are elicited in the majority of individuals after two doses of inactivated COVID-19 vaccines.

Humoral and Cellular Immunity against Different Sars-Cov-2 Variants Is Detectable but Reduced in Vaccinated Kidney Transplant Recipients

Solid organ transplant recipients have an increased morbidity and mortality after SARS-CoV-2 infection. Immune responses after the third/fourth vaccination against SARS-CoV-2 are insufficiently studied in patients after kidney transplantation (KTX). We analyzed immune responses at a median of 4 months after the third/fourth vaccination in KTX patients and compared them to healthy controls. Cellular immunity was assessed using interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) ELISpot assays. Neutralizing antibody titers were assessed against SARS-CoV-2 D614G (wild type) and the variants alpha, delta and omicron by a cell culture-based neutralization assay. Humoral immunity was also determined by a competitive fluorescence assay, using 11 different variants of SARS-CoV-2. Antibody ratios were measured by ELISA. KTX patients showed significantly lower SARSCoV- 2-specific IFN-gamma responses after booster vaccination than healthy controls. However, the SARS-CoV-2 specific IL-2 responses were comparable to the T cell responses of healthy controls. Cell culture-based neutralizing antibody titers were 1.3-fold higher in healthy controls for D614G, alpha and delta and 7.8-fold higher for omicron (p < 0.01). Healthy controls had approximately 2-fold higher concentrations of potential neutralizing antibodies against all 11 variants than KTX patients. However, more than 60% of the KTX patients exhibited antibodies to variants of SARS-CoV-2. In conclusion, KTX patients should be partly protected against SARSCoV- 2, either by cross-reactive T cells, especially those producing IL-2, or by neutralizing antibodies to SARSCoV- 2 variants.

Humoral Response to SARS-CoV-2-Vaccination with BNT162b2 (Pfizer-BioNTech) in Patients on Hemodialysis

mRNA-based SARS-CoV-2 vaccines offer a preventive strategy against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections that is of interest in the care of patients on hemodialysis (HDP). We measured humoral immune responses in 72 HDP after standard vaccination with two doses of the mRNA-based SARS-CoV-2 vaccine BNT162b2 (Pfizer-BioNTech). Antibody responses were evaluated with an anti-SARS-CoV-2 IgG ChemiLuminescent ImmunoAssay (CLIA) two weeks after the second dose. In addition, SARS-CoV-2 IgG was determined in a control of 16 healthy healthcare workers (HCW). The control group of HCW has shown a strong antibody response with a median (MD (Q1;Q3)) antibody titer of 800.0 AU/mL (520.5;800.0). In comparison to HCW, HDP under 60 years of age responded equally (597.0 AU/mL (410.5;800.0), p = 0.051). However, the antibody responses of the HDP negatively correlated with age (r² = 0.2954 p < 0.0001), leading to significantly lower antibody titers in HDP over 60 years (280.0 AU/mL (45.7;477.0), p < 0.0001). To thoroughly understand the immunogenicity of the new mRNA-based vaccines in HDP, longitudinal data on the effectiveness and durability of antibody responses are needed. Modifications of immunization schedules should be considered in HDP with low or without antibody responsiveness after standard vaccination to boost immune reactivity and prolong protective effects in these vulnerable patients.

Allograft infiltration and meningoencephalitis by sars-cov-2 in a pancreas-kidney transplant recipient

Introduction: COVID-19 primarily affects epithelia of the upper and lower respiratory tract. Thus, impairment of kidney function has been primarily attributed to secondary effects like cytokine release or fluid balance disturbances so far. Methods: We provide evidence that SARS-CoV-2 can directly infiltrate a kidney allograft. Results: A 69-year old male pancreas-kidney transplant recipient presented to our hospital with COVID-19 pneumonia and impaired pancreas and kidney allograft function. Kidney biopsy was performed showing tubular damage and an interstitial mononuclear cell infiltrate. RT-PCR from the biopsy specimen was positive for SARS-CoV-2, while being negative in a peripheral blood sample. Subsequently, he suffered from two convulsive seizures. Magnetic resonance tomography suggested meningoencephalitis, which was confirmed by SARS-CoV-2 RNA transcripts in the cerebrospinal fluid. Conclusion: The present case demonstrates that SARS-CoV-2 can infiltrate diverse organs. The patient suffered from COVID-19 pneumonia, meningoencephalitis and nephritis. SARS-CoV-2 binds to its target cells through angiotensin-converting enzyme 2, which is expressed in a broad variety of tissues including the lung, brain and kidney. SARS-CoV-2 thereby shares features with other human coronaviruses including SARS-CoV that were identified as pathogens beyond the respiratory tract as well. The present case should provide awareness that extrapulmonary symptoms in COVID-19 may be attributable to viral infiltration of diverse organs.

Monitoring of general immune status and sars-cov-2 reactive t-cell and humoral immunity facilitates the clinical decision in a severe sars-cov-2-associated pneumonia, meningoencephalitis and gastroenteritis in a pancreas-kidney transplant patient

Introduction: The optimal management in transplant recipients with COVID-19 remains uncertain. The main concern is the ability of immunosuppressed patients to generate sufficient immunity for antiviral protection. Methods: Here, we report on immune monitoring facilitating a successful outcome of severe SARS-CoV-2-associated pneumonia, meningoencephalitis, gastroenteritis and acute kidney and pancreas graft failure in a pancreaskidney transplant recipient. Results: Despite the verylownumbersof circulating B-,NK,andT-cells identified in follow up, a strong SARS-CoV-2 reactive T-cell response was observed. Importantly, we detected T cells reactive to Spike,Membrane and Nucleocapsid proteins of SARS-CoV-2 with majority of T-cells showing polyfunctional proinflammatory Th1 phenotype with advanced differentiation stage at all analyzed time points. Antibodies against Spike protein were also detected with increasing titers in follow up. A correlation between cellular and humoral immunity was observed underscoring the specificity of demonstrated data. Conclusion: We conclude that analyzing the kinetics of non-specific and SARS-CoV-2-reactive cellular and humoral immunity can facilitate the clinical decision on immunosuppression adjustment and allow successful outcome as demonstrated in the current clinical case. While the antiviral protection of the detected SARS-CoV-2-reactive T-cells requires further evaluation, our data prove an ability mounting a strong SARS-CoV-2-reactive T-cell response with functional capacity in immunosuppressed patients.

Impaired cytotoxic cd8⁺ T cell response in elderly COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection induces a T cell response that most likely contributes to virus control in COVID-19 patients but may also induce immunopathology. Until now, the cytotoxic T cell response has not been very well characterized in COVID-19 patients. Here, we analyzed the differentiation and cytotoxic profile of T cells in 30 cases of mild COVID-19 during acute infection. SARS-CoV-2 infection induced a cytotoxic response of CD8⁺ T cells, but not CD4⁺ T cells, characterized by the simultaneous production of granzyme A and B as well as perforin within different effector CD8⁺ T cell subsets. PD-1- expressing CD8⁺ T cells also produced cytotoxic molecules during acute infection, indicating that they were not functionally exhausted. However, in COVID-19 patients over the age of 80 years, the cytotoxic T cell potential was diminished, especially in effector memory and terminally differentiated effector CD8⁺ cells, showing that elderly patients have impaired cellular immunity against SARS-CoV-2. Our data provide valuable information about T cell responses in COVID-19 patients that may also have important implications for vaccine development. IMPORTANCE Cytotoxic T cells are responsible for the elimination of infected cells and are key players in the control of viruses. CD8⁺ T cells with an effector phenotype express cytotoxic molecules and are able to perform target cell killing. COVID-19 patients with a mild disease course were analyzed for the differentiation status and cytotoxic profile of CD8⁺ T cells. SARS-CoV-2 infection induced a vigorous cytotoxic CD8⁺ T cell response. However, this cytotoxic profile of T cells was not detected in COVID-19 patients over the age of 80 years. Thus, the absence of a cytotoxic response in elderly patients might be a possible reason for the more frequent severity of COVID-19 in this age group than in younger patients.