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The expression of HLA-A, -B, -C, and -DR antigens has been analyzed in 145 unrelated Caucasian patients with germ cell tumors of the testis. Eighteen of these patients had pure seminoma, while the remaining patients had nonseminomatous tumors with embryonal carcinoma, teratocarcinoma, choriocarcinoma, and/or yolk sac components, with or without seminoma. Increases were noted in the frequencies of Aw33, B5, DR5, and DRw6 among the patients with pure seminoma, A3 and B7 among the patients with embryonal carcinoma with or without seminoma, and Aw32 among the patients with yolk sac tumor components. A decrease in the frequency of HLA-DR3 was noted in all patients subgroups, although none of these differences were statistically significant after correction for the number of antigens tested. HLA typing results for three affected brothers of patients indicate that, in each family, the affected sibling pair share at least one HLA haplotype. The etiological and prognostic significance of this finding and of the increases in a few HLA antigen frequencies in particular patient groups and the overall decreases in DR3 remain to be determined.

Stomach biopsy specimens from greater than 40 individuals with Campylobacter pyloridis-associated gastritis were examined by light and electron microscopy. The bacteria were consistently seen in two locations: within the gastric mucus and associated with intercellular junctions of gastric epithelial cells. C. pyloridis is suggested to be one of a broad group of spiral bacteria that are adapted to the peculiar niche provided by intestinal mucus. The spiral morphology and the form of motility of these organisms give them a selective advantage in a viscous environment. This point has been demonstrated in vitro by measurement of the velocity of clinical isolates in solutions of methyl cellulose of varying viscosity. The localization of C. pyloridis close to intercellular junctions is proposed to be due to the presence of preferred metabolites or growth factors, e.g., urea and hemin. All isolates show an extremely high urease activity and require hemin for growth.