A variant of calcifying epithelial odontogenic tumor (CEOT) with Langerhans cells is reported. Compared to a typical CEOT, the tumor islands of this case were thin and composed of a small number of polyhedral epithelial cells. Almost no calcification of homogeneous eosinophilic materials was observed. In addition, clear cells which structurally corresponded to Langerhans cell were intermingled in the epithelial islands. These cells stain positively for S-100 protein, lysozome, MT 1, LN-3 and OKT 6 antibodies, but not for keratin antibody. Electronmicroscopic examination revealed the rod-shaped and racket-shaped structures called Birbeck's granules in the cytoplasm of these clear cells. Our observations indicate a variant case of CEOT with Langerhans cells in tumor nests.

Allograft inflammatory factor-1 (AIF-1) is a marker for activated microglia. Unilateral common carotid artery occlusion (UCCAO) was conducted to elucidate mechanisms that regulate AIF-1 expression in C57BL/6 male mice. Immunohistochemical reactivity of microglia against anti-AIF-1 antibody was increased significantly in the brain of this model. The increased AIF-1 production was further confirmed by ELISA using brain homogenate. Real-time PCR demonstrated that the increased AIF-1 production was regulated at the transcriptional level. Serum AIF-1 levels were further examined by ELISA and marked increase was observed on Day 1 of UCCAO. To examine the influence of AIF-1, immunohistochemical staining was performed and revealed that the immunoreactivity against anti-Iba-1 antibody was significantly increased in various organs. Among them, the accumulation of Iba-1+ cells were observed prominently in the spleen. Intraperitoneal injection of minocycline, a potent microglia inhibitor, reduced the number of Iba-1+ cells suggesting microglia activation-dependent accumulation. Based on these results, AIF-1 expression was further examined in the murine microglia cell line MG6. AIF-1 mRNA expression and secretion were up-regulated when the cells were cultured under hypoxic condition. Importantly, stimulation of the cells with recombinant AIF-1 induced the expression of AIF-1 mRNA. These results suggest that increased AIF-1 production by microglia in cerebral ischemia regulate the AIF-1 mRNA expression at least in part by an autocrine manner.

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