HLA Sensitization in the Era of COVID-19: Single-Center Experience.

It is well known that several viral infections are capable of triggering the formation of HLA antibodies; however, an association between SARS-CoV-2 and the development of anti-HLA antibodies is not yet confirmed. In this study, we compared the prevalence of HLA antibody before and after COVID-19 infection in a cohort of 3 groups included 58 healthy nonsensitized employees (HNEs), 130 kidney transplant recipients (KTRs), and 62 kidney transplant candidates. There were no significant changes observed in HLA class I antibodies in any of the groups, but evaluation of antibodies to HLA class II revealed a significant change in the KTR group (P = .0184) after acquiring COVID-19 infection and in the HNE group (P = .0043) when compared to the reported prevalence in a similar population. Although we observed the emergence of convalescent de novo donor-specific antibodies in 2 patients, we did not encounter any rejection episodes in the KTR group. Finally, the results of flow cytometry crossmatch in the HNE group were not consistent with the state of antibodies. In conclusion, COVID-19 infection has the potential to produce class II antibodies but with little effect on preexisting sensitization. These antibodies are likely to be transient and not necessarily causing positive crossmatch with the corresponding antigens at the proper mean fluorescent intensity and therefore should not affect access to transplantation. There is a need for further evaluation to ascertain the genuineness of these antibodies and their exact effect on transplant readiness and outcomes.

Graft-versus-host disease after pediatric liver transplantation: A diagnostic challenge.

BACKGROUND: Graft-versus-host disease (GVHD) is a rare but serious complication after pediatric liver transplantation (LTx). Early diagnosis is difficult due to nonspecific presenting symptoms and non-pathognomonic skin histopathological features. The aim of this article was to describe a case of pediatric GVHD after LTx and to review available data on pediatric GVHD highlighting the diagnostic difficulty. We also propose a diagnostic algorithm to improve the diagnostic capability and increase clinical awareness about this potentially fatal condition. METHODS: We did a comprehensive literatures review on studies on GvHD following pediatric LTx between 1990 and February 2021, chimerism study by short tandem repeat (STR), HLA typing by sequence-specific oligonucleotide (SSO) method, and flowcytometry crossmatch. RESULTS: Our search yielded 23 case reports. The most common clinical manifestations were fever and rash (91%) followed by diarrhea. Mortality rate was 36.8% mainly due to sepsis and organ failure. Diagnosis was challenging and chimerism study to confirm donor engraftment was performed on only half of the cases. Prevalence of "donor dominant HLA one-way matching" typically occurs in homozygous parents-to-child transplantation was 75% in cases with HLA testing. CONCLUSION: So far, there are no available standard diagnostic criteria for GVHD following pediatric LTx. Recognition of multiple risk factors through proper laboratory assessment can predict the occurrence, and early chimerism study can confirm suggestive clinical manifestation. The strong likelihood of developing GVHD in "donor one-way HLA match" and the severe problems imposed by this complication may justify avoidance of HLA homozygous parent's donation.