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Loss of both HLA class I and class II expression in B cell lymphomas is a mechanism of escape from a cytotoxic T lymphocyte (CTL) immune response and will therefore give a strong selective survival advantage in tumours expressing strong immunogenic antigens. We investigated loss of HLA expression using specific antibodies on tissue sections from 254 B cell lymphomas originating from nodal and different extranodal sites in relation to numbers of tumour-infiltrating T cells. Complete loss of HLA class I and II was observed in a minority of the nodal, stomach, and skin lymphomas but in the majority of the lymphomas originating from the testis and the CNS. Interestingly, relatively high percentages of activated CTLs were detected in both primary testicular and CNS lymphomas compared to lymphomas at other sites, with highest percentages in the testis (p < 0.0001). We conclude that loss of both HLA class I and II expression occurs very frequently in lymphomas originating from the testis and the CNS as compared to nodal and some other extranodal sites. The presence of high percentages of activated CTLs in the testicular and CNS lymphomas suggests that loss of HLA expression provides a strong growth advantage for lymphoma cells in these immune-privileged sites.

To determine whether there is a relationship between the presence of H pylon and the various subtypes of intestinal metaplasia in the gastric antrum, 2274 antral gastroscopic biopsies from 533 patients were examined. Hpylon was found in 289 patients. Intestinal The extent of intestinal metaplasia as well as

Whenever intestinal metaplasia was present in the mucosa, 5 ,um sections were cut and stained with Alcian blue pH 2.5/periodic acid Schiff (AB pH 2-5/PAS) and high-irondiamine/Alcian blue for subtyping of intestinal