Temporal correlation between postreperfusion complement deposition and severe primary graft dysfunction in lung allografts

Growing evidence implicates complement in the pathogenesis of primary graft dysfunction (PGD). We hypothesized that early complement activation postreperfusion could predispose to severe PGD grade 3 (PGD-3) at 72 hours, which is associated with worst posttransplant outcomes. Consecutive lung transplant patients (n = 253) from January 2018 through June 2023 underwent timed open allograft biopsies at the end of cold ischemia (internal control) and 30 minutes postreperfusion. PGD-3 at 72 hours occurred in 14% (35/253) of patients; 17% (44/253) revealed positive C4d staining on postreperfusion allograft biopsy, and no biopsy-related complications were encountered. Significantly more patients with PGD-3 at 72 hours had positive C4d staining at 30 minutes postreperfusion compared with those without (51% vs 12%, P < .001). Conversely, patients with positive C4d staining were significantly more likely to develop PGD-3 at 72 hours (41% vs 8%, P < .001) and experienced worse long-term outcomes. In multivariate logistic regression, positive C4d staining remained highly predictive of PGD-3 (odds ratio 7.92, 95% confidence interval 2.97-21.1, P < .001). Hence, early complement deposition in allografts is highly predictive of PGD-3 at 72 hours. Our data support future studies to evaluate the role of complement inhibition in patients with early postreperfusion complement activation to mitigate PGD and improve transplant outcomes.

Implications of blood group on lung transplantation rates: A propensity-matched registry analysis

BACKGROUND

Blood type O lung allografts may be allocated to blood type identical (type O) or compatible (non-O) candidates. We tested the hypothesis that the current organ allocation schema in the United States-based on the Lung Allocation Score-prejudices against the allocation of allografts to type O candidates, given that the pool of potential donors is smaller.

METHODS

We performed a retrospective cohort review of the Organ Procurement and Transplantation Network/United Network of Organ Sharing registry from May 2005 to March 2017 for adult candidates on the waiting list for first-time isolated lung transplantation. Demographic data were compiled and described, and 1:1 nearest-neighbor propensity score matching was used to adjust for age and Lung Allocation Score at listing.

RESULTS

A total of 26,396 candidates met inclusion criteria: 14,329 type non-O and candidates and 12,068 type O candidates. After matching, 11,951 candidates were included in each group. Of these, 77.0% of type non-O underwent lung transplantation vs 73.1% type O (p < 0.001). At 1 year, the waiting list mortality was higher for type O candidates (12.5%) than for non-O candidates (10.1%, p < 0.001). Of those undergoing transplantation, 5-year survival rates were similar.

CONCLUSIONS

Type O candidates experience lower rates of transplantation and higher rates of waiting list mortality compared with matched type non-O candidates. Further evaluation of regional sharing of allografts to increase transplantation rates for type O candidates may be warranted to optimize equity in access to transplants.