Thrombospondin mediates the cytoadherence of Plasmodium falciparum- infected red cells to vascular endothelium in shear flow conditions

Cerebral malaria is thought to involve specific attachment of Plasmodium falciparum-infected knobby red cells to venular endothelium. The nature of surface ligands on host endothelial cells that may mediate cytoadherence is poorly understood. We have investigated the effects of soluble thrombospondin, rabbit antiserum raised against thrombospondin, and human immune serum on cytoadherence of parasitized erythrocytes in ex vivo mesocecum vasculature. Preincubation of infected red cells with soluble thrombospondin or human immune serum inhibits binding of infected red cells to rat venular endothelium. Infusion of the microcirculatory preparation with rabbit antithrombospondin antibodies before perfusion of parasitized erythrocytes also resulted in decreased cytoadherence. In addition, incubation of infected cells with human immune sera obtained from malaria patients significantly inhibited the observed cytoadherence. Our results indicate that thrombospondin mediates binding of infected red cells to venular endothelium and may thus be involved in the pathogenesis of cerebral malaria.     

The effects of postponing prophylactic treatment on long-term outcome in patients with severe hemophilia

To prevent hemophilic arthropathy, prophylactic treatment of children with severe hemophilia should be started before joint damage has occurred. However, treatment is expensive, and the burden of regular venipunctures in young children is high. With the aim of providing information on starting prophylaxis on the basis of individual patient characteristics, the effect of postponing prophylaxis on long-term arthropathy was studied in a cohort of 76 patients with severe hemophilia born between 1965 and 1985. The median age at first joint bleed was 2.2 years (range, 0.2-5.8). Prophylaxis was started at a median age of 6 years (interquartile range [IQR], 4-9), and the median annual clotting factor use on prophylaxis was 1750 IU/kg/y (31 IU/kg/wk). Hemophilic arthropathy was measured by the Pettersson score (maximum, 78 points). At a median age of 19 years, the median Pettersson score was 7 points (IQR, 0-17). After 2 decades of follow-up, the Pettersson score was 8% higher (95% confidence interval, 1%-16%) for every year prophylaxis was postponed after the first joint bleed. This effect was independent of age at Pettersson score, age at first joint bleed, and prophylactic dose used. In conclusion, most patients have their first joint bleed after the age of 2 years. Patients who start prophylaxis soon after the first joint bleed show little arthropathy in adulthood. The longer the start of prophylaxis is postponed after the first joint bleed, the higher the risk of developing arthropathy.     

IgG subclasses of anti-FVIII antibodies during immune tolerance induction in patients with hemophilia A

The eradication of inhibitory antibodies in patients with haemophilia A can be accomplished by frequent administration of high or intermediate doses of factor VIII (FVIII), so-called immune tolerance induction (ITI). This study monitored the distribution of IgG subclasses of anti-FVIII antibodies during ITI. FVIII-specific antibodies of subclass IgG1 were detected in all inhibitor patients tested, anti-FVIII IgG4 in 16, IgG2 in 10 and IgG3 in one of 20 patients analysed. Levels of anti-FVIII IgG1 and IgG4 correlated well with inhibitor titres as measured by Bethesda assay. In low-titre inhibitor patients, anti-FVIII antibodies consisted primarily of subclass IgG1 whereas, anti-FVIII antibodies of subclass IgG4 were more prominent in patients with high titre inhibitors who needed prolonged treatment or who failed ITI. Longitudinal analysis of 14 patients undergoing ITI revealed that the relative contribution of IgG subclasses was constant for most of the patients analysed. In two patients, the relative contribution of IgG4 increased during ITI. Overall, our findings document the distribution and dynamics of anti-FVIII IgG subclasses during ITI. Future studies will need to address whether monitoring the relative contribution of anti-FVIII subclasses IgG1 and IgG4 may be useful for the identification of patients who are at risk of failing ITI.     

IL28B alleles associated with poor hepatitis C virus (HCV) clearance protect against inflammation and fibrosis in patients infected with non-1 HCV genotypes

Genetic polymorphisms near IL28B are associated with spontaneous and treatment-induced clearance of hepatitis C virus (HCV), two processes that require the appropriate activation of the host immune responses. Intrahepatic inflammation is believed to mirror such activation, but its relationship with IL28B polymorphisms has yet to be fully appreciated. We analyzed the association of IL28B polymorphisms with histological and follow-up features in 2335 chronically HCV-infected Caucasian patients. Assessable phenotypes before any antiviral treatment included necroinflammatory activity (n = 1,098), fibrosis (n = 1,527), fibrosis progression rate (n = 1,312), and hepatocellular carcinoma development (n = 1,915). Associations of alleles with the phenotypes were evaluated by univariate analysis and multivariate logistic regression, accounting for all relevant covariates. The rare G allele at IL28B marker rs8099917-previously shown to be at risk of treatment failure-was associated with lower activity (P = 0.04), lower fibrosis (P = 0.02) with a trend toward lower fibrosis progression rate (P = 0.06). When stratified according to HCV genotype, most significant associations were observed in patients infected with non-1 genotypes (P = 0.003 for activity, P = 0.001 for fibrosis, and P = 0.02 for fibrosis progression rate), where the odds ratio of having necroinflammation or rapid fibrosis progression for patients with IL28B genotypes TG or GG versus TT were 0.48 (95% confidence intervals 0.30-0.78) and 0.56 (0.35-0.92), respectively. IL28B polymorphisms were not predictive of the development of hepatocellular carcinoma. CONCLUSION: In chronic hepatitis C, IL28B variants associated with poor response to interferon therapy may predict slower fibrosis progression, especially in patients infected with non-1 HCV genotypes.     

Comparison of eight diagnostic algorithms for liver fibrosis in hepatitis C: new algorithms are more precise and entirely noninvasive

The sequential algorithm for fibrosis evaluation (SAFE) and the Bordeaux algorithm (BA), which cross-check FibroTest with the aspartate aminotransferase-to-platelet ratio index (APRI) or FibroScan, are very accurate but provide only a binary diagnosis of significant fibrosis (SAFE or BA for Metavir F ≥ 2) or cirrhosis (SAFE or BA for F4). Therefore, in clinical practice, physicians have to apply the algorithm for F ≥ 2, and then, when needed, the algorithm for F4 ("successive algorithms"). We aimed to evaluate successive SAFE, successive BA, and a new, noninvasive, detailed classification of fibrosis. The study included 1785 patients with chronic hepatitis C, liver biopsy, blood fibrosis tests, and FibroScan (the latter in 729 patients). The most accurate synchronous combination of FibroScan with a blood test (FibroMeter) provided a new detailed (six classes) classification (FM+FS). Successive SAFE had a significantly (P < 10(-3) ) lower diagnostic accuracy (87.3%) than individual SAFE for F ≥ 2 (94.6%) or SAFE for F4 (89.5%), and required significantly more biopsies (70.8% versus 64.0% or 6.4%, respectively, P < 10(-3) ). Similarly, successive BA had significantly (P ≤ 10(-3) ) lower diagnostic accuracy (84.7%) than individual BA for F ≥ 2 (88.3%) or BA for F4 (94.2%), and required significantly more biopsies (49.8% versus 34.6% or 24.6%, respectively, P < 10(-3) ). The diagnostic accuracy of the FM+FS classification (86.7%) was not significantly different from those of successive SAFE or BA. However, this new classification required no biopsy. CONCLUSION: SAFE and BA for significant fibrosis or cirrhosis are very accurate. However, their successive use induces a significant decrease in diagnostic accuracy and a significant increase in required liver biopsy. A new fibrosis classification that synchronously combines two fibrosis tests was as accurate as successive SAFE or BA, while providing an entirely noninvasive (0% liver biopsy) and more precise (six versus two or three fibrosis classes) fibrosis diagnosis.     

History of non-fatal cardiovascular disease in a cohort of Dutch and British patients with haemophilia

Protein C (PC) deficiency is an autosomal dominant inherited disorder associated with spontaneous and recurrent thrombotic events. Factor V Leiden (FVL) increases the risk of thrombosis in PC-deficient type I families. We have investigated the relationship between PC deficiency genotype and clinical phenotype in a large four-degree Italian family followed since 1988. Methods: PC activity and antigen levels were quantified; sequencing of PC DNA was performed to identify polymorphism. FVL and factor II (G20210A) polymorphism were screened. Results: PC activity ranged from 5% to 9%, and PC antigen levels were 5,3% in two homozygous for PROC missense mutation Arg32Cys; PC activity ranged from 18% to 60% and antigen levels from 21% to 64%, respectively, in 11 heterozygous for Arg32Cys; PC activity was 99% and 120% in two wild type. Of 15, eight were heterozygous for FVL. The two subjects with PC < 6%, homozygous for Arg32Cys and heterozygous for FVL, suffered from thrombosis during childhood. Of 11, six subjects with PC deficiency and heterozygous for FVL showed the first thrombosis at an age between 21 and 54. None of the five PC-deficient subjects, who were wild type for FVL, showed thrombosis. Two subjects with PC > 70%, both heterozygous for FVL developed thrombosis in the presence of another risk factor. This study suggests that FVL and PROC mutations increase the risk of thrombosis in subjects with PC deficiency, which could be considered as a 'variable' risk factor. The thrombosis-prone PC-deficient families carry additional risk factors for thrombosis.     

HIV infection in haemophilia--a European cohort

Ten haemophilia centres in northern Europe have pooled data on 202 haemophilic children who were infected with HIV between 1979 and 1986. All cases were under 16 years of age on 1 July 1985. The age at infection ranged from 1-15 years. Thirty seven cases (18%) had progressed to AIDS by 1 July 1991 and 15 of these have died. Persistent generalised lymphadenopathy has been noted in 102 patients of whom 18 (17%) have developed AIDS. Twenty three of the remaining patients (23%) have not. CD4+ T cell counts have fallen steadily. Of 36 patients who have had shingles since seroconversion, 19 (53%) had counts below 0.2 x 10(9)/l. Thirty five out of 145 patients without shingles (24%) had similar values. The mean IgA concentration in patients with CD4+ T cell counts above 0.5 x 10(9)/l was 2.38 g/l, between 0.2 and 0.5 was 3.07 g/l, and in those with CD4+ T cell counts below 0.2 x 10(9)/l the mean IgA concentration was 4.58 g/l. Treatment patterns have altered between 1989 and 1991, with increased use of zidovudine in patients without AIDS and a marked increase in primary prophylaxis against pneumocystis pneumonia. This has been associated with a decline in the incidence of pneumocystis as an indicator disease in new AIDS cases from 56% in 1989 to 20% in 1991. These observations indicate that persistent generalised lymphadenopathy does not worsen the outlook, but shingles does. Rising IgA concentrations are markers for disease progression. Modern prophylactic regimens are delaying the onset of indicator disease, but CD4 values continue to fall steadily.