The T cell antigen receptor (TCR) recognizes antigen in the form of short peptides bound to a major histocompatibility (MHC) molecule. This review provides a synopsis of the current state of knowledge of the structure and function of the receptor and its possible role in human disease. Analysis of the T cell receptor usage of T-cell lines and clones recognizing the same peptide-MHC complex is beginning to shed light onto the structural basis of the TCR-peptide-MHC complex. Also, it is now apparent that there are two mechanisms by which the TCR can interact with the MHC molecule, either through classical peptide interactions or through super-antigens. Finally, we review the role of specific TCRs in human disease. Current evidence in this area is difficult to interpret; however, it is likely that TCR-mediated disease susceptibility exists, and its basis at either a germline or somatic level will soon be clarified.

We demonstrated diversity of chronic HBV infections in UK patients, suggesting that optimal management requires awareness of the variable patterns of chronic HBV in countries of origin. We also found less-than-optimal clinical management practices, possible gender-based treatment bias, and the need to improve testing for coinfections.

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As physicians, whether serving individual patients or populations, we always have sought to base our decisions and actions on the best possible evidence. The ascendancy of the randomized trial heralded a fundamental shift in the way that we establish the clinical bases for diagnosis, prognosis, and therapeutics. The ability to track down, critically appraise (for its validity and usefulness), and incorporate this rapidly growing body of evidence into one's clinical practice has been named ‘evidence-based medicine’5,6 (EBM).

SUMMARYIn 1994, an outbreak of hepatitis C virus (HCV) infection, genotype 1a, occurred in 30 hypogammaglobulinaemic patients in the UK from one batch of contaminated anti-HCV screened intravenous immunoglobulin. This study aimed to study prospectively the outcome of HCV in hypogammaglobulinaemic patients, and to assess the response to early treatment with interferon-alpha, 6 million units three times weekly for 6 months. Data were collected using standardized questionnaires. Five patients with secondary hypogammaglobulinaemia due to lymphoid malignancy were not treated and all have died of their primary malignancy. Of 25 patients with primary hypogammaglobulinaemia, one resolved HCV infection before treatment, 17 commenced on treatment, and seven declined or treatment was contra-indicated. Thirteen of 17 patients completed therapy and seven (54%) have a sustained response (normal transaminases, negative serum HCV RNA) at 6 and 12 months after treatment. Two of the 12 patients with primary hypogammaglobulinaemia, who were not treated or failed to complete treatment, have cleared the virus. Liver biopsy was performed in patients not clearing HCV and was abnormal in all. Four patients developed liver failure within 2 years, of whom three have died and one has been successfully transplanted. In conclusion, HCV can cause rapid severe liver disease in hypogammaglobulinaemic patients. Early treatment with high-dose interferon-alpha results in a high clearance of HCV.