Multiple HLA class II-restricted melanocyte differentiation antigens are recognized by tumor-infiltrating lymphocytes from a patient with melanoma

Dramatic clinical responses were observed in patient 888 following the adoptive transfer of autologous tumor-infiltrating lymphocytes (TIL). Previously, extensive analysis of the specificity of class I-restricted T cells from patient 888 TIL has revealed that these T cells recognize a mutated, as well as several nonmutated tumor Ags. Additional studies that were conducted on TIL from patient 888 indicated that they contained CD4-positive T cells that recognized the autologous tumor that had been induced to express HLA class II molecules. Tumor-reactive CD4-positive T cell clones were isolated from TIL and tested for their ability to react with Ags that are recognized by HLA class I-restricted, melanoma-reactive T cells. Using this approach, T cell clones were identified that recognized an epitope expressed in both the tyrosinase-related protein 1 and tyrosinase-related protein 2 Ags in the context of the HLA-DRbeta1*1502 class II gene product. Additional clones were found to recognize an epitope of gp100 in the context of the same HLA-DR restriction element. These observations provide an impetus to develop strategies directed toward generating HLA class II-restricted tumor-reactive T cells.     

Induction of cyclooxygenase 2 by Escherichia coli but not Helicobacter pylori lipopolysaccharide in gastric epithelial cells in vitro

Background. Cyclooxygenase 2 (COX‐2) is an inducible enzyme that plays a key role in the synthesis of prostaglandins in response to inflammatory stimuli. It is expressed in the gastric mucosa as part of the response to infection with Helicobacter pylori. The specific interaction between H. pylori and the gastric epithelium that results in COX‐2 expression has not been identified. Methods. In order to investigate the hypothesis that lipopolysaccharide (LPS) from H. pylori plays a role in the induction of cyclooxygenase 2 in the stomach, gastric cell lines MKN‐7 and MKN‐45 were incubated with LPS from either H. pylori NCTC 11637 or Escherichia coli 055:B5. Incubation of cells with live H. pylori NCTC 11637 was also carried out as a positive control. Cells were then analysed for COX‐2 protein and mRNA and prostaglandin E2 synthesis. Results. Cyclooxygenase 2 protein and mRNA expression was induced by E. coli LPS and live H. pylori, but not by H. pylori LPS. Prostaglandin E₂ synthesis increased in a dose‐dependent manner in both cell lines with E. coli but not H. pylori LPS. Conclusions. H. pylori LPS is of low biological activity when compared with E. coli LPS in its ability to induce the expression of cyclooxygenase 2 and synthesis of prostaglandin E₂. This may provide one mechanism by which H. pylori minimizes the inflammatory response in the gastric mucosa, allowing chronic infection.     

Lysophosphatidylethanolamine acyltransferase activity is elevated during cardiac cell differentiation

This work attempts to explain several aspects of the response of plasminogen to 6-aminohexanoate (6-AH). These responses include the overall fluorescent changes that occur when plasminogen binds the ligand, the changes shown by the individual domains when they bind the ligand, and the changes in structure shown by the holoprotein when it binds 6-AH. The results have implications for understanding the physicochemical behavior of all kringle based proteins.     

Elevation in phosphatidylethanolamine is an early but not essential event for cardiac cell differentiation

The biosynthesis of phosphatidylethanolamine was examined during differentiation of P19 teratocarcinoma cells into cardiac myocytes. P19 cells were induced to undergo differentiation into cardiac myocytes by the addition of dimethyl sulfoxide to the medium. Immunofluorescence labeling confirmed the expression of striated myosin 10 days postinduction of differentiation. The content of phosphatidylethanolamine increased significantly within the first 2 days of differentiation. [1,3-(3)H]Glycerol incorporation into phosphatidylethanolamine was increased 7.2-fold during differentiation, indicating an elevation in de novo synthesis from 1, 2-diacyl-sn-glycerol. The mechanism for the increase in phosphatidylethanolamine levels during cardiac cell differentiation was a 2.8-fold increase in the activity of ethanolaminephosphotransferase, the 1,2-diacyl-sn-glycerol utilizing reaction of the cytidine 5'-diphosphate-ethanolamine pathway of phosphatidylethanolamine biosynthesis. Incubation of P19 cells with the phosphatidylethanolamine biosynthesis inhibitor 8-(4-chlorophenylthio)-cAMP inhibited the differentiation-induced elevation in phosphatidylethanolamine levels but did not affect the expression of striated myosin. The results suggest that elevation in phosphatidylethanolamine is an early event of P19 cell differentiation into cardiac myocytes, but is not essential for differentiation to proceed.