Homologous serum hepatitis and measles prophylaxis; a report to the Medical Research Council

The Evolution of the Safety of Plasma Products from Pathogen Transmission-A Continuing Narrative

Chronic recipients of plasma products are at risk of infection from blood-borne pathogens as a result of their inevitable exposure to agents which will contaminate a plasma manufacturing pool made up of thousands of individual donations. The generation of such a pool is an essential part of the large-scale manufacture of these products and is required for good manufacturing practice (GMP). Early observations of the transmission of hepatitis by pooled plasma and serum led to the incorporation of heat treatment of the albumin solution produced by industrial Cohn fractionation of plasma. This led to an absence of pathogen transmission by albumin over decades, during which hepatitis continued to be transmitted by other early plasma fractions, as well as through mainstream blood transfusions. This risk was decreased greatly over the 1960s as an understanding of the epidemiology and viral aetiology of transfusion-transmitted hepatitis led to the exclusion of high-risk groups from the donor population and the development of a blood screening test for hepatitis B. Despite these measures, the first plasma concentrates to treat haemophilia transmitted hepatitis B and other, poorly understood, forms of parenterally transmitted hepatitis. These risks were considered to be acceptable given the life-saving nature of the haemophilia treatment products. The emergence of the human immunodeficiency virus (HIV) as a transfusion-transmitted infection in the early 1980s shifted the focus of attention to this virus, which proved to be vulnerable to a number of inactivation methods introduced during manufacture. Further developments in the field obviated the risk of hepatitis C virus (HCV) which had also infected chronic recipients of plasma products, including haemophilia patients and immunodeficient patients receiving immunoglobulin. The convergence of appropriate donor selection driven by knowledge of viral epidemiology, the development of blood screening now based on molecular diagnostics, and the incorporation of viral inactivation techniques in the manufacturing process are now recognised as constituting a "safety tripod" of measures contributing to safety from pathogen transmission. Of these three components, viral inactivation during manufacture is the major contributor and has proven to be the bulwark securing the safety of plasma derivatives over the past thirty years. Concurrently, the safety of banked blood and components continues to depend on donor selection and screening, in the absence of universally adopted pathogen reduction technology. This has resulted in an inversion in the relative safety of the products of blood banking compared to plasma products. Overall, the experience gained in the past decades has resulted in an absence of pathogen transmission from the current generation of plasma derivatives, but maintaining vigilance, and the surveillance of the emergence of infectious agents, is vital to ensure the continued efficacy of the measures in place and the development of further interventions aimed at obviating safety threats.

Epidemia de hepatite veiculada por gamaglobulina contaminada

Os autores estudaram uma epidemia de Hepatite B em uma instituição localizada no bairro de São Cristovão na cidade do Rio de Janeiro, Brasil. Ocorreu um total de 35 casos: 30 entre os funcionários da instituição e cinco entre familiares de funcionários. Todos os casos foram considerados de hepatite aguda benigna; apenas dois não tiveram icterícia. Clinicamente, chamou-lhes a atenção um importante envolvimento articular: artralgias intensas, com grande restrição dos movimentos, durante o período de incubação e que regrediram completamente logo que a icterícia tornou-se evidente. A distribuição cronológica foi típica de infecção simultânea em fonte única. A investigação epidemiológica revelou que essa fonte foi um produto terapêutico derivado do sangue humano: gamaglobulina. As injeções foram feitas com seringas descartáveis e, ironicamente, com o objetivo de prevenir hepatite. Em dois dias de aplicação, cerca de 120 funcionários receberam a injeção de gamaglobulina, entre os quais 27 desenvolveram hepatite. O período de incubação médio foi de 116 dias. 0 Ag HB, testado em 26 pacientes, foi positivo em 12 (46,2%); oito pacientes com tempo de doença inferior a duas semanas, foram todos positivos. O surto epidêmico ocorreu em condições que caracterizaram um estudo experimental, não planejado, em seres humanos. Os autores estudaram, além do surto epidêmico de São Cristovão, oito casos vinculados ao serviço hospitalar onde trabalhavam. Esses casos apresentaram características que os distinguiram dos casos de hepatite comumente all tratados. Todos os pacientes eram de elevada classe social, com o antecedente de terem tomado injeção de gamaglobulina, da mesma procedência daquela que originou o surto epidêmico de São Cristovão. Nesses casos o período de incubação médio foi de 106 dias. Seis dos oito pacientes foram testados para o Ag HB, que foi positivo em cinco. Onze partidas da gamaglobulina foram testadas, em laboratórios de referência da Organização Mundial de Saúde, encontrando-se o Ag HB em seis (54,5%J. Os autores concluem que houve alguma falha grave no processo de preparo da gamaglobulina em apreço. E por isto deve-se ter reservas quanto á noção difundida de que esse medicamento está isento do risco de transmitir o vírus hepatite.

Freedom from transmission of hepatitis-B of gamma-globulin and heat-inactivated plasma protein fraction prepared from contaminated human plasma by fractionation with solid-phase polyelectrolytes

Plasma contaminated with hepatitis B surface antigen (HBsAg) and shown by others to be infectious when injected in a dilution of 1:1,000,000 in chimpanzees, was fractionated by a solid-phase polyelectrolyte (PE) procedure for its content of plasma protein fraction (PPF) and gamma-globulin (immune serum globulin; ISG). Quantitative Ausria II radioimmunoassays showed that nearly half the HBsAg was bound by the PE and could be eluted at low pH, while the rest was found in the heat-inactivated PPF. When the ISG was concentrated to 16%, the 13 mg/kg (comparable to a human dose) was injected intramuscularly in 6 chimpanzees, or when the PPF was heated at 60 degrees C for h and injected intravenously in 2 chimpanzees, there was no clinical or laboratory evidence of hepatitis B infection after 12 months, although 1 chimp of 2 who received the same material showed a borderline positive anti-HBsAg antibody result on one of 52 weekly serum samples. Since the new PE fractionation method is essentially nondenaturing, and simpler than the classical ethanol procedures, it was important to establish the noninfectivity of the final products.