Expression of costimulatory molecules, B7-1 and B7-2 on human gastric carcinoma.
Costimulation of T cells via B7-1 and B7-2 molecules on a tumor has been shown to be important for eliciting cell-mediated antitumor immunity. We studied the surface expression of B7-1 and B7-2 in 24 cases of gastric carcinoma from the primary locus, 20 cases of metastatic carcinoma from malignant ascites, 20 cases of benign gastric mucosa and 7 gastric carcinoma cell lines by two-color flow cytometry with mAb CD80 and CD86. The B7-1 and B7-2 molecules were expressed by 6 cell lines, and 1 cell line showed the predominant expression of B7-2 but not B7-1. Almost all patients with primary gastric carcinoma and benign gastric mucosa showed high levels of expression of the B7-1 and B7-2, revealing approximately 40%-60% positive cells. However, the percentage of B7-1-positive cells of poorly differentiated primary carcinomas was significantly lower than that of well-differentiated carcinoma and normal mucosa (P < 0.01). Furthermore, all of the metastatic carcinoma cells revealed consistently very low or undetectable levels of expression of the B7-1 molecule, only 8% (mean) of cells being positive, despite showing higher levels of B7-2 expression. Thus, it seems likely that decreased or deleted expression of B7-1 correlates with the grade of tumor differentiation, tumor progression and metastasis. These results suggest that the B7-1 molecule on the gastric carcinoma bearing CD80+CD86+ is abrogated during tumor invasion and/or metastasis, and the tumor finally acquires the CD80-CD86+ phenotype. Consequently, inadequate B7-1 costimulation may contribute to the escape of tumors from destruction by the host's immune system.
Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Tsukuba-City, Ibaraki, Japan.
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Koyama
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Maruyama
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Adachi
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Nozue
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000096:biosynthesis*; D018122:B7-1 Antigen / Q000096:biosynthesis*; D051940:B7-2 Antigen; D002277:Carcinoma / Q000276:immunology* / Q000473:pathology; D005434:Flow Cytometry; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D013274:Stomach Neoplasms / Q000276:immunology* / Q000473:pathology; D019139:Tumor Escape
D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; C497964:CD86 protein, human; D008562:Membrane Glycoproteins