Search

Background: Virus inactivation of plasma can be achieved by photodynamic methods in the presence of phenothiazine dyes such as methylene blue (MB). Subsequent filtration may increase the efficacy of virus inactivation and reduce adverse effects of WBC contamination and MB.Study Design and Methods: This study examined the effect of filtration with three different filters (MBF1, MBF2, and MBF3) on MB concentration, residual cells, coagulation factors, and activation measures of coagulation, fibrinolysis, and complement in MB-treated (1 microM/L) plasma units.Results: Filtration reduced the concentration of MB by > or = 89 percent. WBCs were depleted by 92 percent (MBF1) and >99.9 percent (MBF2 and MBF3). Treatment with MB significantly decreased the coagulation potency from levels in untreated plasma, as measured by thromboplastin time ratio (112 +/- 18% vs. 95 +/- 11%), activated partial thromboplastin time (40 +/- 3 sec vs. 44 +/- 3 sec), thrombin time (16.9 +/- 1.1 sec vs. 18.6 +/- 1.5 sec), factor VIII (1.09 +/- 0.21 U/mL vs. 0.85 +/- 0.13 U/mL), and vWF (0.94 +/- 0.65 U/mL vs. 0.65 +/- 0.24 U/mL). Filtration did not further decrease these values, while factor XI (0.75 +/- 0.22 U/mL vs. 0.37 +/- 0.20 U/mL) and prekallikrein values decreased in MB plasma units filtered with the MBF3. In addition, activated factor XII (0.7 +/- 0.5 microg/L vs. 4.5 +/- 1.0 microg/L) increased.Conclusion: WBCs and MB can be eliminated from MB-treated plasma units by filtration. Differences in biocompatibility of the different filters, especially the influence on the contact phase of coagulation, must be taken into consideration. [ABSTRACT FROM AUTHOR]

Background: Noninvasive fetal RHD genotyping might become a valuable tool in decision making on antenatal Rh prophylaxis, which is currently in routine practice for all D- pregnancies in several countries. This study provides a large-scale validation study of this technology to address questions concerning feasibility and applicability of its introduction into clinical routine., Study Design and Methods: Real-time polymerase chain reaction (PCR) targeting RHD Exons 5 and 7 was applied for the detection of fetal-specific RHD sequences in maternal plasma. A total of 1113 women in 6 to 32 weeks (median, Week 25) of pregnancy were recruited. All of them were serologically typed as D- according to current German guidelines. DNA was extracted via a spin-column method and a novel automated approach using magnetic tips. Real-time PCR results were compared with postnatal serology and discrepancies further elucidated by DNA sequencing from a newborn's buccal swab., Results: Sensitivities of fetal RHD genotyping were 99.7 percent (spin columns) and 99.8 percent (magnetic tips), thus comparable with serology (99.5%). The detection of weak D variants was more reliable by real-time PCR. Specificities of fetal RHD genotyping were 99.2 percent (spin columns) and 98.1 percent (magnetic tips), which is lower than serology (>99.7%). Automation achieved significantly higher yields of cell-free fetal DNA., Conclusion: This prospective clinical trial revealed that routine determination of the fetal D status from maternal plasma is feasible. Noninvasive fetal RHD genotyping can be considered as sensitive as the traditional postnatal serologic assay.

Background: Novel gel centrifugation test (GCT) cards were evaluated with respect to their ability to estimate the quantity of IgG on RBCs and the determination of the IgG subclasses IgG1 and IgG3., Study Design and Methods: In 65 patients with a positive DAT, the amount of IgG-gamma-, IgG1, and IgG3 on RBCs was examined by use of GCT cards and flow cytometry (FC) in parallel. The results were correlated with the presence or absence of hemolysis. In addition, D+ RBCs were studied after sensitization with anti-D sera from 22 alloimmunized pregnant women., Results: The amount of IgG on the RBCs as determined by GCT dilution cards correlated with FC (r=0.70, p < 0.0001). IgG subclass results as determined by GCT IgG subclass cards were confirmed by FC in 14 cases with an anti-IgG-gamma-chain titer > or =300, whereas IgG subclass cards were not suitable in cases with anti-IgG-gamma-chain titers less than 300. In 44 patients with 2+ or 3+ DAT in the GCT and anti-IgG-gamma-chain titer < or =30, no hemolysis was observed, whereas hemolysis occurred in 13 of 14 patients with an anti-IgG-gamma-chain titer > or =300. GCT data obtained by IATs with anti-D sera were concordant with FC results., Conclusion: There is a correlation between the amount of RBC-bound IgG and immune hemolysis. The GCT cards that detect the anti-IgG-gamma-chain may be useful to predict hemolysis in patients with a 2+ or 3+ DAT in the GCT. The diagnostic value of GCT cards for IgG subclass testing should be investigated further.