Post-Surgical Remodeling of Circulating Monocytes Identifies CD86 Expression on Non-Classical Monocytes as a Prognostic Indicator in Pancreatic Ductal Adenocarcinoma.

Circulating myeloid cells are critical regulators of pancreatic ductal adenocarcinoma (PDAC) progression. However, their postoperative dynamics and clinical relevance remain poorly defined. In a prospective longitudinal study, blood was collected from PDAC patients prior to surgery and on postoperative day 7. Flow cytometry was used to characterize monocytes, including classical (CM), intermediate (IMM), and non-classical (NCM) subsets, along with regulatory and co-stimulatory molecules (CD71, CD40, CD141, CD80, CD86, PD-L1). Cytokine levels (IL-6, IL-10, TNF-α, IL-1β) were quantified by ELISA and correlated with clinical parameters and survival. Total monocytes and CM increased significantly at day 7, whereas IMM and NCM decreased. CD71, CD141, CD80, and CD86 expression were significantly altered across subsets, with the most pronounced reduction observed in CD86 expressing NCM. CD86 expressing NCM correlated inversely with systemic bilirubin but not CEA, lymphocytes, thrombocytes, or hospital stay. IL-6 and IL-10 increased postoperatively; IL-10 showed a tendency toward inverse correlation with CD86+ NCM. Low CD86 expression on NCM at day 7 was associated with reduced survival and higher relapse probability. CD86 expression on NCMs is profoundly reduced after PDAC surgery and serves as a prognostic biomarker linked to inflammation, bilirubin metabolism, survival, and recurrence. Postoperative monocyte profiling may improve risk stratification and inform early clinical decision-making.