The killer-cell Ig-like receptor (KIR) 2DL4 (CD158d) acts as a receptor for human leukocyte antigen (HLA)-G and is expressed on almost all human natural killer (NK) cells. The expression and function of KIR2DL4 in other hematopoietic cells is poorly understood. Here, we focused on human mast cells, which exhibit cytotoxic activity similar to that of NK cells. KIR2DL4 was detected in all examined human cultured mast cells established from peripheral blood derived from healthy volunteers (PB-mast), the human mast cell line LAD2, and human nonneoplastic mast cells, including those on pathologic specimens. An agonistic antibody against KIR2DL4 decreased KIT-mediated and IgE-triggered responses, and enhanced the granzyme B production by PB-mast and LAD2 cells, by activating Src homology 2-containing protein tyrosine phosphatase (SHP-2). Next, we performed a coculture assay between LAD2 cells and the HLA-G þ cancer cells, MCF-7 and JEG-3, and showed that KIR2DL4 on LAD2 cells enhanced MMP-9 production and the invasive activity of both cell lines via HLA-G. Immunohistochemical analysis revealed that the direct interaction between HLA-G þ breast cancer cells and KIR2DL4 þ tissue mast cells (observed in 12 of 36 cases; 33.3%) was statistically correlated with the presence of lymph node metastasis or lymphvascular invasion (observed in 11 of 12 cases; 91.7%; x 2 ¼ 7.439; P < 0.01; degrees of freedom, 1) in the clinical samples. These findings suggest that the KIR2DL4 on human mast cells facilitates HLA-G-expressing cancer invasion and the subsequent metastasis.

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We recently reported increased sphingosine kinase 1 (SPHK1) and decreased neutral sphingomyelinase 2 (NSMase2) gene expression in myelodysplastic syndromes and acute leukemia. This alteration is supposed to change the cellular sphingolipid metabolites; however, positive correlations were observed between daunorubicin (DA)-IC50 and the SPHK1 message but not between DA-IC50 and NSMase2 messages, when 16 different leukemia cell lines were used to analyze the relationship between gene expressions and chemosensitivity against DA. Using two cell lines with either the highest or lowest SPHK1 expression, cellular ceramides and sphingosine 1-phosphate (S1P) were quantified by liquid chromatography/mass spectrometry. Increased ceramide was observed in DA-sensitive, but not in DA-resistant cell lines treated with low doses of DA. Upon DA treatment, S1P decreased more in the sensitive cell lines than in resistant cell lines. A SPHK inhibitor recovered the DA sensitivity of DA-resistant cells. The modulation of SPHK1 gene expression by either overexpression or using siRNA affected the DA sensitivity of representative cell lines. Results clearly show that SPHK1 is both a good marker to predict the DA sensitivity of leukemia cells and a potential therapeutic target for leukemia with high SPHK1 expression, and suggest that the sphingolipid rheostat plays a significant role in DA-induced cytotoxicity.

Intraductal tubulopapillary neoplasm (ITPN) of the pancreas, a novel entity included in the World Health Organization 2010 classification, accounts for <1% of all pancreatic exocrine neoplasms and the number of reported cases is limited in the English literature. Herein we describe the cytologic features of ITPN with invasive carcinoma showing expansile growth on endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) cytology. A 74-year-old male patient is presented with a 6.2 cm irregular mass in the head of the pancreas. Microscopic examination of EUS-FNA material showed abundant branching clusters of cells, with some scattered discohesive cells. High power magnification revealed tubular and cribriform patterns with central lumina, containing mucinous or proteinaceous secretions. The constituent cells were relatively uniform and showed mild to intermediate nuclear atypia. Intracytoplasmic mucin was not identified. On cell-block preparation, luminal spaces of clusters contained wispy luminal mucin. Immunohistochemically, constituent cells were positive for MUC1 and MUC6, and were negative for MUC5AC. The large cribriform and tubular clusters with luminal spaces containing wispy mucin were considered to be diagnostic clues for the cytologic diagnosis of ITPN by EUS-FNA. MUC1, MUC6, and MUC5AC immunohistochemistry for cell-block preparation appears to be a useful adjunctive tool to confirm the diagnosis. On EUS-FNA, ITPN should be included in the differential diagnosis of a pancreatic mass lesion showing good circumscription.