AimCellular CD81 is a well characterized hepatitis C virus (HCV) entry factor, while the relevance of soluble exosomal CD81 in HCV pathogenesis is poorly defined. We performed a case-control study to investigate whether soluble CD81 in the exosomal serum fraction is associated with HCV replication and inflammatory activity.Patients and MethodsFour cohorts were investigated, patients with chronic hepatitis C (n = 37), patients with chronic HCV infection and persistently normal ALT levels (n = 24), patients with long term sustained virologic response (SVR, n = 7), and healthy volunteers (n = 23). Concentration of soluble CD81 was assessed semi-quantitatively after differential centrifugation ranging from 200 g to 100,000 g in the fifth centrifugation fraction by immunoblotting and densitometry.ResultsSoluble CD81 was increased in patients with chronic hepatitis C compared to healthy subjects (p = 0.03) and cured patients (p = 0.017). Patients with chronic HCV infection and persistently normal ALT levels and patients with long term SVR had similar soluble CD81 levels as healthy controls (p>0.2). Overall, soluble CD81 levels were associated with ALT levels (r = 0.334, p = 0.016) and severe liver fibrosis (p = 0.027).ConclusionCD81 is increased in the exosomal serum fraction in patients with chronic hepatitis C and appears to be associated with inflammatory activity and severity of fibrosis.

A series of 6 controlled experiments in C3H/He mice were performed to evaluate nonspecific immunotherapeutic regimens with a transplantable murine bladder tumor (MBT2). Immunotherapeutic agents studied included live Bacillus Calmette-Guerin (BCG) preparations in varying doses and strains (Tice, Pasteur, and Glaxo), Re mutant glycolipid (ReG) from Salmonella typhimurium, BCG cell wall skeletons (CWS), CWS plus B4 glycolipid fraction of ReG, and Keyhole-Limpet Hemocyanin (KLH). Animals received an intradermal MBT2 inoculation and were then randomized to treatment and control (saline treated) groups. Immunotherapy was administered intralesionally 1 day after tumor transplantation. Tumors were excised by amputation at a volume of 400 mm. and animals were later rechallenged with tumor inocula, again treated, and followed for tumor incidence growth rate and survival. No antitumor affect was observed with ReG, CWS or CWS plus B4. KLH immunotherapy did result in measurable antitumor effect. Consistent and statistically significant (p less than 0.01) antitumor responses as measured by prolonged survival and decreased growth rate were observed with Tice and Pasteur strains of BCG in doses ranging from 5 X 10(5) to 1 X 10(7) colony forming units per animal. Doses in excess of 10(7) units were found to decrease antitumor response. Glaxo strain BCG had no beneficial effect when used in the maximal dose (10(6) colony forming units) that could be administered. In animals immunized with intermediate doses of live Tice or Pasteur strain BCG in the study, effective long term immunity to transitional cell carcinoma was observed. Although many new immunotherapeutic agents have been advocated in other tumor models, to date we have found Tice and Pasteur strains of live BCG to be the most effective agents in the treatment of transitional cell carcinoma.

Despite effective treatment of existing tumors, patients with bladder cancer remain at risk of developing new tumors. Effective immunotherapy may lower that risk. To test this hypothesis, mice that had survived transitional cell carcinoma (MBT2) transplantation with the aid of bacillus Calmette-Guerin immunotherapy were randomized and tested for long term protective immunity against bladder carcinoma. Fifty-one tumor-free mice that had survived tumor challenge 10 to 15 months previously were randomized into 3 groups to receive intradermal tumor .noculation and intraperitoneal levamisole, intralesional Tice strain bacillus Calmette-Guerin, or intralesional saline. Fifteen previously unchallenged animals also received tumor and intralesional saline. All 3 groups of survivors had less tumor growth (p less than 0.01) than nonsurviving controls. Even among survivors, additional bacillus Calmette-Guerin immunization, but not levamisole treatment, significantly inhibited tumor growth (p less than 0.01). A 2nd experiment compared 22 nonimmune mice, 21 mice preimmunized intravenously with 300 micrograms of bacillus Calmette-Guerin cell walls, and 18 mice that had survived MBT2 by 8 months after live bacillus Calmette-Guerin treatment. Nonimmune and survivor groups were randomly subdivided into saline or treatment groups. Cell wall-preimmunized mice were divided into matching groups according to footpad response to purified protein derivative. The cell-wall preimmunized and nonimmune mice received the immunostimulant P3+Re-glycolipid or the carrier solution alone. The group of survivors received either intralesional saline or live bacillus Calmette-Guerin. Both bacillus Calmette-Guerin and saline-treated groups had significantly less tumor growth (p less than 0.001) than nonsurviving controls. Animals treated with P3-Re-glycolipid (with or without preimmunization with cell wall) did not differ from nonsurviving control. Footpad response to purified protein derivative did not correlate with tumor growth in these mice. Our results suggest that intralesional bacillus Calmette-Guerin immunotherapy can afford long term protection from transplanted bladder cancer, and that live bacillus Calmette-Guerin is superior to levamisole and P3 + Re-glycolipid + bacillus Calmette-Guerin cell walls in the treatment of bladder cancer.

Transitional cell carcinoma is known to be an immunogenic tumour. This immunogenicity has been the basis of a search for effective immunotherapeutic agents and for the evaluation in this study of two additional agents, keyhole-limpet haemacyanin (KLH) and immune ribonucleic acid (RNA) extract. The results in this animal model showed KLH to be a potent non-specific stimulant of the immune response which caused both a reduction in tumour growth and a prolongation of animal survival (p = 0.01). No anti-tumour effects were observed with either local or systemic RNA.

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