Prophylaxis of hepatitis C with intramuscular immunoglobulin: clinical and economic appraisal.
Hepatitis C virus (HCV) affects millions of individuals worldwide. In most cases, HCV infection progresses to chronic liver disease and, subsequently, to liver cirrhosis and hepatocellular carcinoma. HCV is transmitted by the parenteral route, for example by transfusion of blood or blood products, injection during drug abuse, etc., and by the inapparent parenteral route (penetration of the virus through difficult-to-identify microlesions present on the skin or mucosae), for example, sexual exposure or household exposure to infected contacts, etc. The cost of chronic hepatitis C and its sequelae is high in both financial and human terms. At present, only anti-HCV screening of blood/organ/tissue donors and universal precautions for the prevention of blood-borne infections are recommended for HCV prevention. Before the discovery of the main aetiological agent of non-A, non-B hepatitis (HCV), several randomised controlled clinical trials demonstrated that standard intramuscular immunoglobulin exerted a preventive effect on post-transfusional and sexual and /or horizontal transmission of non-A, non-B hepatitis. When serological tests for HCV infection became available, bimonthly inoculation of standard unscreened intramuscular immunoglobulin (prepared from plasma pools containing about 2% of anti-HCV-positive units) was demonstrated to significantly prevent sexually transmitted HCV infection. The immunoglobulin used contained high titres of anti-HCV neutralising antibodies (anti-E2 neutralisation of binding assay), whereas currently available commercial screened immunoglobulin (prepared from anti-HCV-negative blood units) did not. This finding suggested that anti-HCV neutralising antibodies are concentrated only in anti-HCV-positive units (which are currently discarded). Thus, anti-HCV hyperimmune globulin (HCIg) can be produced only from anti-HCV-positive units. The neutralising titre can be increased by the exclusive use of units with higher titres of neutralising antibodies. Unlike other hyperimmune globulins, which are produced from a limited number of selected donors, HCIg should be produced from a large number of units so as to contain neutralising antibodies to the different HCV strains. HCIg will have a number of advantages: (i) it is easy to produce and inexpensive; (ii) it has a long half-life, allowing infrequent administration; (iii) new additional viral inactivation procedures have been introduced to eradicate transmission of infection, and (iv) it may be possible to neutralise all the emerging HCV strains. HCIg could be used in all individuals at risk of HCV infection (sexual partners, haemodialysis patients, etc), in preventing reinfection of transplanted livers, and perhaps also in the treatment of chronic hepatitis C, alone or associated with other drugs.
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Istituto di Malattie Infettive, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, Naples, Italy. piazzama@unina.it
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