Surface phenotype and functions of tumor‐infiltrating dendritic cells: CD8 expression by a cell subpopulation

Abstract

Although the function and significance of tumor-infiltrating dendritic cells (TIDC) in the immune response to tumor have never been clearly demonstrated, their location suggests that they play a critical role in the presentation of tumor antigen to specific T cells. We studied the morphological and functional characteristics of interstitial dendritic cells (DC) located inside tumors obtained by injection of cancer cells into syngeneic rats. Single and double immunostaining of tumor sections revealed a dense network of cells which expressed class II major histocompatibility complex (MHC II) molecules. Cell morphology and surface markers were characteristic of DC populations in other tissues. These DC were in close contact with tumor cells and increased in number as the tumor grew larger. Unexpectedly, a subpopulation of morphologically characteristic TIDC expressed both CD8 and MHC II molecules. TIDC were purified from tumors by gradient centrifugation and immunobeads and characterized by morphology, ultrastructural study and surface markers studied by flow cytometry. TIDC were negative for the CD5 molecule (a pan T cell marker), and were not labeled with 3.2.3 monoclonal antibody (mAb) (an NK cell marker) or with Ki-M2R mAb (a macrophage marker). A subpopulation of TIDC expressed the CD8 molecule, confirming the in situ results. TIDC expressed high levels of class I and class II MHC molecules and the adhesion molecule ICAM-1. This expression is compatible with effective antigen presenting function. Purified TIDC triggered rapid and high levels of proliferation of tumor-immune T cells in vitro, demonstrating the potential of these cells to constitutively process and present tumor-associated antigens.

Immunohistochemical localization of CD1a-positive putative dendritic cells in human breast tumours

“…A close spatial association was demonstrated between CD1a + cells and tumour cells using double staining with CD1a and CAM 5.2 antibodies, confirming observations by others in different tumour types (Kato et al, 1990;Kondo et al, 1990;Chaux et al, 1993). Periductal distribution of CD1a + cells was noted in DCIS and grade I tumours, and in higher grade tumours CD1a + cells were intermixed with tumour cells.…”

Phenotype of Rat Monocytes During Acute Kidney Allograft Rejection: Increased Expression of NKR‐P1 and Reduction of CD43

“…There is increasing evidence that CD8 may occur in cells other than T cells and NK cells, and a population of Ox8-positive monocytes has been detected by flow cytometry in a rat model of sublethal total-body irradiation followed by thermal injury [55]. In addition, rat Kupffer cell precursors [51], a subpopulation of tumour-infiltrating dendritic cells in rats [56], certain dendritic cells in the thymus and spleen of normal mice [57,58] and peritoneal as well as alveolar macrophages [59] express the CD8 antigen.…”

CD4+CD25+ Tregs control the TRAIL-dependent cytotoxicity of tumor-infiltrating DCs in rodent models of colon cancer

“…Tumor stroma is richly invaded by host cells, which include tumorinfiltrating DCs (TIDCs) identified in virtually all human cancers (1-7) and experimental tumor models (8)(9)(10)(11)(12). Immunological functions of TIDCs remain only partly understood (13).…”