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Randomized and cohort studies have provided evidence confirming the hypothesis, based on in-vitro observations, that the use of very high-purity factor VIII (FVIII) concentrates, either immuoaffinity chromatography purified or produced by recombinant DNA technology, may slow immunological deterioration in human immunodeficiency virus (HIV)-infected haemophiliacs, while high-purity concentrates, produced by ion-exchange chromatography, did not produce a benefit. Even though these data clearly indicate that very high-purity concentrates should be preferred for the replacement therapy of HIV-positive haemophiliacs, there are little data, based on direct comparison, supporting the use of very high-purity concentrates rather than high-purity preparations, which are less expensive. In an attempt to address this issue, we prospectively compared CD4 cell counts and changes of clinical status in 18 HIV-positive haemophiliacs, randomly assigned either to receive the treatment with a very high-purity FVIII concentrate, purified by immunoaffinity chromatography, or a high-purity product, produced by ion-exchange chromatography. All patients had CD4 lymphocyte counts below 300 μL(-1) , were negative for the hepatitis B surface antigen and the HIV p24 antigen, and were receiving antiretroviral treatment with Zidovudine for at least 6 months. There were no significant changes of CD4 cell counts over the 96-week follow-up period or between the two groups. No signficant differences between the two groups were detected in the occurrence of AIDS-defining diagnoses (one in each group). On the whole, no striking benefit is conferred to the immune status of asymptomatic HIV-positive haemophiliacs by using either of these high-purity and very high-purity FVIII concentrates for 96 weeks. Larger prospective randomized trials are needed to establish definitely whether it is necessary to resort to very high-purity concentrates or it is sufficient to use high-purity concentrates to slow the fall of CD4 cell counts that occurs in HIV-positive haemophiliacs. Randomized trials, based on clinical end-points, are also needed to demonstrate whether slowing the fall in CD4 cells results in clinical benefits, delaying the occurrence of AIDS.

Summary This article describes prenatal diagnosis (PND) of haemophilia B (HB) within the framework of Italian haemophilia centres and genetics laboratories. The study details the experience from six haemophilia genetic centres (three in the North, one in the Centre and two in the South of Italy) and summarizes the different techniques used to perform PND of HB during the last 15 years. To date, the Italian HB database includes 373 characterized unrelated patients and their genetic information has permitted the identification of 274 carriers of childbearing age. This database represents the main instrument for timely and precise PND. Sixty-six prenatal diagnoses were performed on 52 HB carriers whose average age at the time was 34 (ranging from 24 to 44 years). In 44 cases, genetic counselling for carrier status determination was performed before pregnancy, while eight were not studied prior to pregnancy. Foetal samples were obtained by chorionic villus sampling in 52 cases, by amniocentesis in 12 while two were diagnosed by analysis of free foetal DNA obtained from maternal peripheral blood. In 35 (53%) pregnancies the foetus was female. For 31 men (47%), haemophilia status was determined by analysis of previously determined informative markers or familial mutations (12 affected and 19 unaffected). There may be more than one laboratory involved in the PND diagnostic pathway (providing DNA extraction, karyotype analysis, gender determination, maternal contamination detection, molecular diagnosis and sequencing). Good communication between all the parties, coordinated by the haemophilia centre, is essential for a successful and rapid process.

Inhibitor antibodies to transfused factor VIII pose significant challenges in the management of haemophilia A patients. The main concern is the inefficacy of replacement therapy in patients with high-titre antibodies, who have a shorter life-span and a greater morbidity compared to subjects without inhibitors. The ultimate goal in treating these patients is to eliminate the inhibitor antibody entirely, allowing the recommencement of specific replacement therapy. The results of an immune tolerance regimen based on pharmacokinetic parameters are reported here. In 12 high-responder haemophilia A patients immune tolerance induction (ITI) was attempted with daily administration of factor VIII concentrates of very high purity, either plasma-derived or produced by recombinant-DNA technology. Patients were given 100 IU kg(-1) day(-1) until the inhibitor was shown to be absent by at least two negative assays 1 month apart, with normal recovery of infused factor VIII and normal half-life (> 6 h), as assessed after a 3-day washout period. After the patient was judged to be inhibitor-free, immune tolerance treatment was continued with unmodified factor VIII doses for 2 months. Doses were thereafter gradually reduced and finally, regular prophylaxis by administration of 25 IU kg(-1) three times weekly was instituted. Immune tolerance was achieved in 10 of the 12 patients (including six of seven with long-standing inhibitors) within a median time of 8 months. Outcome of immune tolerance was not influenced by age at start of ITI nor by the interval between inhibitor development and ITI. The success rate and the inhibitor disappearance time of our immune tolerance regimen, utilizing high-purity factor VIII, agrees with those reported by other investigators.