Expression of the CD44 molecule was examined in a variety of human brain tumours, brain metastases and normal brain. Immunohistological staining with several CD44 antibodies demonstrated differential expression of the CD44 molecule among different brain tumour types. CD44 was strongly expressed in high-grade gliomas and weakly expressed in meningiomas, medulloblastomas and normal brain. Northern blot analysis revealed the presence of 3 major CD44 mRNAs of 1.6, 2.2, and 5.0 kb in glioblastomas and a mRNA of 5.6 kb in meningiomas. CD44 expression was also detected by flow cytometric analysis on cultured cells derived from a variety of human brain tumours including glioblastomas and meningiomas.

Adhesion molecules, a family of cell-surface molecules, are likely to be of central importance in mediating cell-extracellular matrix and specific cell-cell interactions within both neoplastic and inflammatory sites. The recently discovered expression of adhesion molecules on glioma cells, tumor-infiltrating lymphocytes, and endothelial cells within the tumor offers insight into the molecular basis of the interactions both between the glioma cell and surrounding heterologous cell types within the tumor environment, and between the tumor cell and the extracellular matrix. Such interactions suggest that these molecules may play roles in the homing of immune cells to these tumors and in regulating the extent of local tumor invasion. The ability to modulate adhesion molecule expression on either immune cells or their respective ligands on gliomas provides an approach to modify cell-cell interactions that may be used to increase tumor kill by the immune system. A similar approach in the modulation of adhesion molecules involved in tumor cell adhesion to the extracellular matrix or endothelial cells may be a method to limit local invasion in these lesions.

The present study demonstrates interleukin-1 (IL-1) production by human glioblastoma cells both in vitro and in vivo. The presence of IL-1 alpha and IL-1 beta transcripts was analyzed in 4 cell lines. IL-1 alpha mRNA was expressed constitutively in one cell line whereas constitutive IL-1 beta mRNA could not be detected in any of the cell lines. IL-1 alpha transcripts could be induced with phorbol myristate acetate (PMA) or PMA plus lipopolysaccharide (LPS) in 2 of 4 cell lines and IL-1 beta mRNA in 2 of 4 cell lines. Culture fluid from these cell lines was tested for the presence of IL-1 using a specific radio-immuno-assay for either IL-1 alpha or IL-1 beta. In agreement with the results on RNA, one of 4 cell lines was found to constitutively produce IL-1 alpha but not IL-1 beta. After treatment with PMA and LPS, IL-1 alpha was detected in the culture fluid from two other lines and IL-1 beta in the medium from three lines. That the IL-1 produced by these cell lines was biologically active was confirmed in a two step thymocyte proliferation assay. IL-1 like activity was detected in all samples that were positive in the radio-immuno-assay. Finally, immunohistological analysis on fresh frozen tumour sections provided evidence for IL-1 production by glioblastoma cells in vivo. Fourteen out of 28 glioblastomas were stained with an anti-IL-1 alpha monoclonal antibody while none of them was stained with an anti-IL-1 beta antibody.

of antibody to hepatitis C virus in an isolated Canadian Inuit settlement. Can J Infect Dis 1991;2(2):71-73. Sera from 720 inha bitants of Baker Lake. Northwest Territories , a commu nity with high rates of hepatitis A and B infection, were tested for antibody to hepalilis C virus by commercial enzyme-linked immunosorben t assay. Only two individuals (0 .3%) were positive. a 63-year-old female and an unrelated 10-year-old male . Neither individual was a t increased risk of h epalilis C virus exposure. Th e results of this study indicate that hepalilis C virus infection is no more common in this northern Canadian Inuit setUem e ntthan it is in the blood donor population of southern Canada. the Inuit population of northern Canada (1) . Previous sera-epidemiological surveys have documented that a pproximately 80% of adults have been infected with the hepatitis A virus, and 25 to 35% have serologic evidence of either ongoing or previous hepatitis B virus infection (2 -4). Hepatitis D virus infection has also been reported in the Canadian North; however, t.he true prevalence of this virus remains to be determined (5).Recently, Chao and colleagues (6) reported the discovery of a single-stranded RNA virus responsible for t.he majority of cases of what had previously been referred to as non-A,non-B, hepatitis. The virus has since been designated hepatitis C. Preliminary data indicate that non-neutralizing antibodies to hepatitis C virus (anti-HCV) are present in the circulation of 80% of patients with parenterally acquired infection and 60% of patients with nonparenteral or sporadic forms of hepatitis C virus infection (7). The prevalence of anti-HCV in Red Cross blood donors living in southern Canada is approximately 0.5% (unpublished data) .To determine the prevalence of hepatitis C virus infection in a Canadian Inuit population, anti-HCV antibodies were tested in stored sera from an isolated Inuit settlement where a high prevalence of hepatitis A and B virus infection had been previously documented (3). PATIENTS AND METHODS Study population:The geographic and demographic features of Baker Lake, Northwest Territories have been described in detail in previous publications (3,8). Briefly, this is a prosperous settlement located 200 miles inland from the northwest coast of Hudson Bay. Sera were obtained in February 1980 when the population of t.he community was 850. Approximately 95% of t.he inhabitants were Inuit and 5% Caucasians. Informed consent to test blood samples for serologic evidence of viral hepatitis was obtained through a nursing station interpreter from all adu lts and parents or guardians of children involved in t.he study. Laboratory methods: A total of 720 sera (85% of the community's population) had been stored at -70°C when first obtained. Thawing and refreezing of the samples had been confined to that required for hepatitis A and B viruses serologic testing. Anti-HCV was tested by an Ortho anti-HCV enzyme-linked immunosorbent assay (ELISA) test system which incorporates recombinant hepatitis C virus a...