Impaired intratumoral dendritic cell function and potential predictive value of dendritic cells markers for metastasis in malignant salivary gland tumors

Background: The differentiation between primary and metastatic salivary gland neoplasms (SGNs) helps in determining appropriate management strategies, including the need for additional diagnostic tests, surveillance, or aggressive treatment. The purpose of this study was to identify and quantify the immature and mature dendritic cells (DCs) in metastatic and no metastatic SGNs and determine its association with clinicopathological findings. Material and methods: Cross-sectional, observational, and descriptive study that includes 33 malignant salivary gland neoplasms [MSGN (6, 18.1% metastatic)], and 22 pleomorphic adenomas (PA), as a control group. Clinical and histopathological characteristics were obtained. Immunohistochemistry for human leukocyte antigen D-related (HLA-DR), CD1a, CD83, and Ki-67 proteins was done. Positive intra- and peritumoral DCs were counted. Results: Individuals with MSGN had a lower density of intratumoral HLA-DR+ cells than those with PA (p=0.001), Ki-67 immunostaining was significantly higher in MSGN than in PA (6% vs. 1.4%, p<0.001). Metastatic MSGN showed less intratumoral CD1a+ than non-metastatic (3.2 vs. 165.1, p=0.001). No differences in intra- and peritumoral CD83+ cells were found between benign and malignant SGN. Conclusions: These results suggest that the immune-protective function of intratumoral DCs is compromised in MSGNs. DCs markers may represent useful prediction tools for metastases in salivary gland malignancies, with crucial implications in the implementation of appropriate disease management strategies.