In this respect, the presentation of the exogenous FVIII may not be sufficient for initiating an immune response. In the presence of danger conditions (i.e. severe bleeds, trauma or surgery with major tissue injury), the foreign protein is intensively presented (high-dose and/or prolonged treatment) in association with signals

that up-regulate the cellular T and B lymphocyte response. On the other hand, regular exposure to lower doses of antigen, in the absence of danger signals, which occurs in regular prophylaxis, may induce the tolerization of the foreign protein. This hypothesis is supported by recent studies showing a key role of the intensity of treatment at the first FVIII exposures: both in the CANAL cohort, which investigated selleck products 366 consecutive previously untreated children (PUPS) born between 1990 and 2000 from 14 centres in Europe and Canada [24], and in the combined analysis of data on 236 patients (FVIII <2%) from the four recombinant FVIII (rFVIII) registration PUPS studies [25], surgical and prolonged (≥5 days) FVIII exposure at first treatment,

and high FVIII dose (≥50 IU/kg) during the first 50 ED were associated with a twofold to threefold increase in the risk of inhibitor development. www.selleckchem.com/products/icg-001.html These data are also likely to explain the higher risk of inhibitor development in patients with an early age at first FVIII exposure, detected in previous studies and only at univariate analysis in the CANAL and other studies (Table 1). For this reason, an intensive treatment at initial exposure has been considered the most significant determinant (three points) in the prognostic score determined from the CANAL data [10]. This see more score includes the genetic factors previously mentioned (high-risk F8 mutation and positive inhibitor family history, each two points) and may

help to identify patients at high (>50%, score ≥3), intermediate (about 25%, score 2) or low (about 6%, score 0) risk of inhibitors. In agreement with the ‘danger model’, the CANAL study [24] and a previous case–control Italian study [26] showed by regression models, which take into account other potential inhibitor risk factors, a 60–70% reduction in inhibitor risk in patients on regular prophylaxis compared with those receiving on-demand treatment (Table 1). The most controversial issue of treatment-related risk factors remains the type of FVIII concentrate administered [1]. The CANAL study also investigated the risk of inhibitor development with respect to plasma-derived vs. recombinant products, and switching between FVIII products [27].