CD169 (sialoadhesin) is a sialic acid receptor that is specifically expressed on macrophages, including lymph node sinus macrophages. Animal studies suggest that CD169+ macrophages in lymph nodes have properties in preventing cancers; however, the role of these cells in the pathogenesis of human tumors has not been clarified. In order to determine the significance of CD169+ macrophages in patients with malignant melanoma (MM), we evaluated tissue samples from 93 patients to investigate the CD169 expression in regional lymph nodes (RLNs) and determine the relationships of this expression with overall survival and various clinicopathological factors. Consequently, a high density of CD169+ cells was found to be significantly associated with a longer overall survival in the patients with MM (P = 0.001). A multivariate analysis showed that the density of CD169+ cells was an independent prognostic factor, and a positive correlation was noted between the density of CD169+ macrophages and the density of CD8+ cytotoxic T cells infiltrating tumor tissues. The in vitro experiments demonstrated a high CD169 expression in interferon (IFN)-α-stimulated macrophages. Moreover, IFN-α-producing macrophages were identified surrounding CD169+ macrophages, and a few CD303+ pDCs secreted IFN-α in the RLNs. These data suggest that CD169+ macrophages in RLNs are closely involved in T cell-mediated antitumor immunity and may be a useful marker for assessing the clinical prognosis and monitoring antitumor immunity in patients with MM.
- Received September 24, 2014.
- Revision received June 30, 2015.
- Accepted July 6, 2015.
- Copyright © 2015, American Association for Cancer Research.