Immunohistochemical analysis of the aggregation of CD1a-positive dendritic cells in resected specimens and its association with surgical outcomes for patients with gallbladder cancer

•We examined CD1a-positive dendritic cell (CD1a-DC) infiltration in gallbladder cancer.•The group with high CD1a-DC infiltration had fewer patients with distant metastasis.•A high level of CD1a-DC infiltration was associated with longer overall survival.•High CD1a-DC infiltration was also associated with longer disease-specific survival.•S100-DC and tumor-infiltrating lymphocyte statuses were without effect on survival. Gallbladder cancer (GBC) is an aggressive malignancy with a poor prognosis. Antigen-presenting dendritic cells (DCs) play a central role in antitumor immunity. DCs expressing CD1a (CD1a-DCs) are considered immature DCs. The aim of this study was to evaluate the clinical impact of CD1a-DC infiltration into GBC tissue. Seventy-five patients with GBC (excluding non-invasive and intramucosal cancer) were enrolled. Immunohistochemistry for CD1a, S100 and CD8 was performed using representative surgically resected specimens. The cases were divided into a high CD1a-DC group (27 cases, 36%) and low CD1a-DC group (48 cases, 64%) according to the degree of CD1a-DC infiltration/aggregation. The high CD1a-DC group contained fewer patients with distant metastasis (P = 0.039) and more patients given postoperative chemotherapy (P = 0.038). The high CD1a-DC group had significantly longer overall survival (P = 0.001) and disease-specific survival (P = 0.002) than the low CD1a-DC group. In contrast, S100-DC and CD8+ tumor-infiltrating lymphocyte statuses were without effect on OS or DSS. The results of multivariate analyses indicated that the degree of infiltration/aggregation of CD1a-DCs was an independent prognostic factor associated with a favorable prognosis after surgery.