# Analysis of HLA genotype in the recipients’ different tissues after haploidentical hematopoietic stem cell transplantation

## TL;DR

This study examines how HLA genotypes in different tissues change after a type of stem cell transplant, showing that blood samples often reflect the donor's genes while other tissues retain the patient's original genes.

## Contribution

The study provides the first systematic analysis of HLA genotype changes across multiple tissues after haploidentical hematopoietic stem cell transplantation.

## Key findings

- Peripheral blood samples mostly showed donor HLA genotypes after transplantation.
- Buccal swabs retained the patient's original HLA genotype in most cases.
- Saliva samples showed mixed results, with some retaining the patient's genotype and others showing donor genotype.

## Abstract

Peripheral blood samples are widely used in HLA genotyping due to their easy accessibility and the high-quality DNA from nucleated leukocytes. However, in cases of disease relapse requiring a second transplantation, clinicians encounter significant challenges in performing HLA genotyping and interpreting complex results from patients who have undergone haploidentical hematopoietic stem cell transplantation (haplo-HSCT). Furthermore, systematic studies investigating the impact of haplo-HSCT on recipients’ HLA genotypes across different tissues remain scarce. Therefore, this study aims to analyze HLA genotypes in various tissues of the recipient after haplo-HSCT.

A total of 66 patients who received haplo-HSCT were enrolled, with peripheral blood, buccal swab and saliva samples collected for HLA genotyping. The results were compared with pre-HSCT HLA genotypes of the patients and their respective donors.

The majority of peripheral blood samples (55/57) exhibited the donor’s HLA genotype, whereas most buccal swabs (54/62) retained the patient’s pre-HSCT genotype. Among 20 salivary samples, 45% of patients retained their pre-HSCT genotype, while 30% exhibited the donor’s genotype. Notably, chimerism and HLA loss were detected in buccal swab and saliva cells of certain recipients. More strikingly, one patient’s buccal sample displayed complete donor HLA genotype replacement.

These findings enhance our comprehension of the genetic effects of haplo-HSCT on the recipient’s different tissues and provide valuable insights for the rational selection of tissue samples and data interpretation in HLA genotyping for patients who underwent allogenic HSCT.