COVID-19 vaccine does not alter panel reactive antibody or flow cytometric cross match in kidney transplant candidates

Immunomodulatory Effect of COVID-19 on HLA-Antibody Profile in Renal Transplant Recipients

Background/Objectives: The novel coronavirus disease 2019 (COVID-19) has led to significant morbidity and mortality among kidney transplant recipients. SARS-CoV-2 has been hypothesized to cause an unusual immunological dysregulation triggering alloimmunity and leading to graft rejection. Methods: This prospective observational cohort study assessed 321 kidney transplant recipients who had COVID-19 infection. After the infection, patients' sera were tested for the presence of anti-HLA de novo DSA and non-DSA specificities. Logistic regression analysis and a stepwise multivariable logistic regression analysis were used to analyze the independent risk factors associated with the development of antibodies, adjusting for known confounders. The variables evaluated were acute COVID-19 characteristics (i.e., presentation, and need for hospitalization), demographic characteristics (i.e., age, gender, and primary renal disease), clinical characteristics (i.e., various comorbidities), and post-COVID-19 sequelae. Results: Anti-HLA de novo DSA developed in 18.7% of patients, while anti-HLA class I and class II non-DSA antibodies developed de novo in 84 (26.3%) and 83 (25.9%) patients, respectively. The development of DSA, HLA-DQ, and HLA-DR antibodies was predicted by the history of graft rejection. Obesity appeared to be protective against the emergence of de novo DSA. De novo DSA and HLA-DR antibody formation was positively linked with intravenous immunoglobulin use, CMV-hyperimmune globulin use, and decreased doses of immunosuppression during acute infection. Better allograft function during the acute disease was a protective factor against the formation of HLA-DQ and HLA-DR antibodies. Positive predictors of de novo DSA development were graft biopsy and the reactivation of EBV after infection. Conclusions: These findings suggest that the SARS-CoV-2 virus has an immunomodulatory effect and may be associated with an increased mortality in this population.

Low incidence of de novo HLA antibodies after COVID-19 vaccination: A cohort study of patients awaiting kidney transplantation

BACKGROUND

Antibodies against human leukocyte antigen (anti-HLA Abs) are associated with an increased risk of allograft loss. Herein, we report the prospective follow-up for anti-HLA Abs formation in 103 patients with end-stage kidney disease on the waiting list for transplantation who underwent COVID-19 vaccination.

PATIENTS AND METHODS

Sera were tested before and after vaccination using Luminex technology. The cohort comprised of 62 males and 41 females with a mean age of 56 ± 14 years. The patients received BNT162b2 (80.4%), mRNA-1273 (18.5%), AZD1222 (0.40%), or ChAdOx1-S (0.80%) vaccine. Patients were tested before and within 119 ± 50, 95 ± 46 and 25 ± 26 days after the first, second, and third dose of the vaccine, respectively.

RESULTS

No significant change in calculated panel reactive antibody (cPRA) after vaccination was seen. Although 98.1% of patients had no change in anti-HLA Abs profile or cPRA after vaccination, two patients (1.9%) developed de novo anti-HLA Abs against class I or II HLA antigens. In those two patients, the cPRA changed from 0% and 63% at baseline to 9% and 90% after vaccination, respectively. Both patients received the BNT162b2 mRNA-based vaccine. The earliest detected anti-HLA Abs was 18 days after the first dose.

CONCLUSION

In rare cases, new anti-HLA antibodies were observed after COVID-19 vaccination, with potential implications for transplantation. The low incidence of this phenomenon is outweighed by the clinical benefits of vaccination.

Detection and management of HLA sensitization in candidates for adult heart transplantation

Heart transplantation (HT) remains the preferred therapy for patients with advanced heart failure. However, for sensitized HT candidates who have antibodies to human leukocyte antigens , finding a suitable donor can be challenging and can lead to adverse waitlist outcomes. In recent years, the number of sensitized patients awaiting HT has increased likely due to the use of durable and mechanical circulatory support as well as increasing number of candidates with underlying congenital heart disease. This State-of-the-Art review discusses the assessment of human leukocyte antigens antibodies, potential desensitization strategies including mechanisms of action and specific protocols, the approach to a potential donor including the use of complement-dependent cytotoxicity, flow cytometry, and virtual crossmatches, and peritransplant induction management.

Analysis of Cross-sectional and Longitudinal HLA and Anti-viral Responses After COVID Infection in Renal Allograft Recipients: Differences and Correlates

BACKGROUND

Characterization of anti-HLA versus anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) immune globulin isotypes in organ transplant recipients after coronavirus disease 2019 (COVID-19) infection has not been reported. We aimed to determine changes in anti-HLA antibodies in renal transplant patients with COVID-19 and compare the immunoglobulin and epitope-binding pattern versus anti-SARS-CoV-2 antibodies.

METHODS

This is a cross-sectional study of 46 kidney transplant recipients including 21 with longitudinal sampling. Using a semi-quantitative multiplex assay, we determined immunoglobulin (Ig) M, IgA, IgG, and IgG1-2-3-4 antibodies against Class I and Class II HLA, and 5 SARS-CoV-2 epitopes including the nucleocapsid protein and multiple regions of the spike protein.

RESULTS

Fourteen of 46 (30%) patients had donor-specific anti-HLA antibodies (donor-specific antibody [DSA]), 12 (26%) had non-DSA anti-HLA antibodies and 45 (98%) had anti-SARS-CoV-2 antibodies. Most DSAs targeted HLA-DQ (71%), with a dominant IgG isotype and IgG1 subtype prevalence (93%), and/or IgG3 (64%), followed by IgG2 (36%). Comparatively, there was a higher prevalence of IgA (85% versus 14%, P = 0.0001) and IgM (87%, versus 36%, P = 0.001) in the anti-SARS-CoV-2 antibody profile, when compared to DSAs, respectively. Anti-SARS-CoV-2 antibody profile was characterized by increased prevalence of IgM and IgA, when compared to DSAs. The median calculated panel reactive antibody before COVID-19 diagnosis (24%) tended to decrease after COVID-19 diagnosis (10%) but it was not statistically significant ( P = 0.1).

CONCLUSIONS

Anti-HLA antibody strength and calculated panel reactive antibody in kidney transplant recipients after COVID-19 do not significantly increase after infection. Although the IgG isotype was the dominant form in both HLA and SARS-CoV-2 antigens, the alloimmune response had a low IgA pattern, whereas anti-SARS-CoV-2 antibodies were high IgA/IgM.

Update on COVID-19 vaccination in pediatric solid organ transplant recipients

BACKGROUND

COVID-19 vaccination has been successful in decreasing rates of SARS-CoV-2 infection in areas with high vaccine uptake. Cases of breakthrough SARS-CoV-2 infection remain infrequent among immunocompetent vaccine recipients who are protected from severe COVID-19. Robust data demonstrate the safety, immunogenicity, and effectiveness of several COVID-19 vaccine formulations. Importantly, Pfizer-BioNTech BNT162b2 mRNA COVID-19 vaccine studies have now included children as young as 5 years of age with safety, immunogenicity, and effectiveness data publicly available. In the United States, emergency use authorization by the Federal Drug Administration and approval from the Centers for Disease Control/Advisory Committee on Immunization Practices have been provided for the 5- to 11-year-old age group.

METHODS

Members of the International Pediatric Transplant Association (IPTA) provide an updated review of current COVID-19 vaccine data with focus on pediatric solid organ transplant (SOT)-specific issues.

RESULTS

This review provides an overview of current COVID-19 immunogenicity, safety, and efficacy data from key studies, with focus on data of importance to pediatric SOT recipients. Continued paucity of data in the setting of pediatric transplantation remains a challenge.

CONCLUSIONS

Further studies of COVID-19 vaccination in pediatric SOT recipients are needed to better understand post-vaccine COVID-19 T-cell and antibody kinetics and determine the optimal vaccine schedule. Increased COVID-19 vaccine acceptability, uptake, and worldwide availability are needed to limit the risk that COVID-19 poses to pediatric solid organ transplant recipients.

SARS-CoV-2 mRNA vaccination is not associated with the induction of anti-HLA or non-HLA antibodies

BACKGROUND

SARS-CoV-2 vaccination is strongly recommended in kidney transplant recipients (KTR) and dialysis patients. Whether these vaccinations may trigger alloantibodies, is still debated.

METHODS

In the current study we evaluated the effect of SARS-CoV-2 mRNA vaccines on anti-Human Leukocyte Antigen (HLA) and 60 anti-non-HLA antibody profiles in clinically stable KTR and dialysis patients. In total, we included 28 KTR, 30 patients on haemodialysis, 25 patients on peritoneal dialysis and 31 controls with a positive seroresponse 16-21 days after the first dose of either the SARS-CoV-2 mRNA BNT162b2 or mRNA-1273 vaccine. Both anti-HLA and anti-non-HLA antibodies were determined prior to vaccination and 21 to 35 days after the second vaccine dose.

RESULTS

Overall, the proportion of patients with detectable anti-HLA antibodies was similar before and after vaccination (class I 14% vs. 16%, p = 0.48; class II 25% before and after vaccination). After vaccination, there was no pattern in 1) additionally detected anti-HLA antibodies, or 2) the levels of pre-existing ones. Additional anti-non-HLA antibodies were detected in 30% of the patients, ranging from 1 to 5 new anti-non-HLA antibodies per patient. However, the clinical significance of anti-non-HLA antibodies is still a matter of debate. To date, only a significant association has been found for anti-non-HLA ARHGDIB antibodies and long-term kidney graft loss. No additionally developed anti-ARHGDIB antibodies or elevated level of existing anti-ARHGDIB antibodies was observed.

CONCLUSION

The current data indicate that SARS-CoV-2 mRNA vaccination does not induce anti-HLA or anti-non-HLA antibodies, corroborating the importance of vaccinating KTR and dialysis patients.