For RT-PCR, 1 μg of total RNA, M-MLV RTase

(ReverTra Ace, Toyobo, Tokyo, selleckchem Japan) and oligo-dT primers were used. Polymerase chain reaction (PCR) amplification was performed using DNA polymerase (Takara EX Taq, Takara, Tokyo, Japan) and specific primers for human mRNA sequences (Table 1). The glyceraldehyde 3-phosphate dehydrogenase mRNA was used as a housekeeping gene. Following After PCR, an annealing of primers for 1 minute, and an extension at 72°C for 2 minutes (the annealing temperature and cycle number are shown in Table 1), PCR products were subjected to agarose gel electrophoresis. Approximately 1 × 104 HuCCT1 cells per well in 96-well plates were cultured for 24 hours. Supernatants were then tested for human IL-10 via enzyme-linked immunosorbent assay (ELISA) (R&D Systems). Data were analyzed using the Welch t test; P

< 0.05 was considered statistically significant. Immunohistochemistry revealed that IgG4-positive plasma cells were scattered within and around cancerous nests to various degrees in most cases (Fig. 1). In the cases with marked infiltration, the IgG4-positive cells were prominent with intermingling of other inflammatory cells. Figure 1C shows the number of IgG4-positive cells/HPF in extrahepatic cholangiocarcinomas from common bile ducts, gallbladder, and the Papilla of Vater, but there was no significant difference in IgG4-positive cell counts among anatomical locations of extrahepatic cholangiocarcinomas. Therefore,

they were integrated as shown in Fig. 1D. Consequently, the combined quantitative evaluation revealed that 23 (43%) of 54 cholangiocarcinoma ACP-196 ic50 patients had ≥10 IgG4-positive cells/HPF. PIK3C2G There was no correlation between the density of IgG4-positive cells and any clinicopathological factor including age, sex, anatomical location (common bile ducts, gallbladder, and the Papilla of Vater), or the histological differentiation (well, moderate, and poor) of extrahepatic cholangiocarcinoma. Representative images of immunostaining are shown in Fig. 2. Expression of HLA-DR was found in some infiltrating immunocompetent cells. Moreover, HLA-DR–positive cholangiocarcinoma cells were also found in 33 of 54 cases. HLA-DR expression in tumor cells showed uniformity and metastatic foci in lymph nodes as well as main tumors expressing HLA-DR. In contrast, the expression of costimulatory molecules (CD80 and CD86) was mostly faint or absent. Only four cases were clearly positive for CD86 in cholangiocarcinoma cells, and all of them were positive for HLA-DR. No cases evidently expressed CD80. Cholangiocarcinoma cells expressing HLA-DR but lacking costimulatory molecules (CD80 and CD86) were found in 29 of 54 cases (54%) and suggested to act as nonprofessional APCs inducing IL-10–producing anergy T cells. The relation between IgG4 reactions and HLA-DR and costimulatory molecules in cancer cells is shown in Fig. 3.