Low CD4 and high CD8 percentages prior to lung transplantation are linked to significantly decreased survival in the first post-transplant year

Intro: Our previous study showed a significant relationship between both abnormally low and high CD4+/CD8+ T-lymphocyte ratios (rCD) prior to lung transplantation (LuTx) and decreased allograft survival. We aimed to evaluate the relationship between the respective percentages of pre-LuTx CD4+ and CD8+ T-lymphocytes (CD4%; CD8%) and the survival in the first post-LuTx year. Methods: LuTx recipients (LTRs) with available CD4% and CD8% measurements within 24h prior to LuTx between 2010 and 2019 were included. LTRs were categorized into four groups based on the CD4% and CD8% quartiles. One year survival rate for these groups was analyzed by Gehan-Breslow-Wilcoxon analysis. Results: Of 308 LTRs, 206 (66.9%) fulfilled the inclusion criteria. For CD4%, Q1 was determined as 32% of CD4% or lower (n=48; 23.3%), Q2 as 33-41% (n=55; 26.7%), Q3 as 42-48% (n=51 24.7%) and Q4 as 49% and higher (n=52; 25.2%). Regarding CD8%, Q1 included patients with CD8% 19% or lower (n=50; 24.3%), Q2 with 20-25% (n=47; 22.8%), Q3 with 26-33% (n=58; 28.2%) and Q4 with 34% and higher (n=51; 24.7%). The analysis showed significantly worse survival within the first year post LuTx in CD4% Q1 (p=0.0495) and CD8% Q4 (p=0.0439). Conclusion: LTRs in the lowest CD4% and the highest CD8% quartile demonstrated worse survival in the first post-LuTx year, consistent with our previous results linking low pre-LuTx rCD to decreased survival. Although an abnormally high rCD before LuTx was also associated with inferior graft survival, no relationship between survival and the highest CD4% or the lowest CD8% quartile was observed. Further analyses are required to elaborate these findings.