# Increased Eplet Mismatch Load and Reduced Immunosuppressive Exposure Elevate the Risk of Baseline Lung Allograft Dysfunction

## TL;DR

Higher eplet mismatch and lower immunosuppressive drug levels increase the risk of poor lung function after lung transplants.

## Contribution

Identifies eplet mismatch load and immunosuppressive exposure as novel risk factors for baseline lung allograft dysfunction.

## Key findings

- BLAD patients had higher eplet mismatch burden compared to non-BLAD patients.
- Lower tacrolimus TTR and MPA AUC0–12 levels were observed in BLAD patients.
- DR/DQ eplet mismatches and MPA AUC0–12 were independently linked to worse lung function.

## Abstract

Background/Objectives: Some lung transplant (LungTx) recipients do not achieve the expected lung function within the first year, a condition known as baseline lung allograft dysfunction (BLAD). Our objective was to analyze the risk factors associated with BLAD, focusing on the variables associated with a higher risk of developing a more intense alloimmune response. Methods: We carried out a prospective study including 88 LungTx recipients. BLAD was defined as failure to reach 80% of the predicted value for forced expiratory volume in one second (FEV1) and/or forced vital capacity (FVC) on two tests conducted at least three weeks apart. Tacrolimus time in therapeutic range (TTR) and mycophenolic acid area under the curve (MPA AUC0–12h) were measured at the third month. Donor–recipient compatibility was assessed using HLA eplet mismatch analysis, performed via HLA Matchmaker 3.1. Results: BLAD patients showed greater eplet mismatch burden (67, IQR 20 vs. 55, IQR 22, p = 0.018) and had been exposed to a lower TTR (26.6%, IQR 14.0% vs. 39.6%, IQR 24.3%, p = 0.039) and less frequently to an adequate third-month MPA AUC0–12 > 30 mg × h/L (57.1% vs. 89.2%, p = 0.020). DR/DQ eplet mismatches (β = −0.348, p = 0.002) and third-month MPA AUC0–12 (β = 0.285, p = 0.009) were independently associated with six-month predicted FEV1%. Conclusions: Among other variables, BLAD and initial lung graft function are associated with greater eplet discordance and lower immunosuppressive drug exposure, suggesting a potential role of underlying alloimmune responses in their pathogenesis.