Leukodepletion as a point-of-care method for monitoring HIV-1 viral load in whole blood.

In order to limit the interference of HIV-1 cellular nucleic acids in estimating viral load (VL), the feasibility of leukodepletion of a small whole-blood (WB) volume to eliminate only leukocyte cell content was investigated, using a selection of filters. The efficacy of leukocyte filtration was evaluated by counting, CD45 quantitative PCR, and HIV-1 DNA quantification. Plasma HIV-1 was tested by real-time reverse transcription (RT)-PCR. A specific, miniaturized filter was developed and tested for leukocyte and plasma virus retention, WB sample dilution, and filtration parameters in HIV-1-spiked WB samples. This device proved effective to retain >99.9% of white blood cells in 100 µl of WB without affecting plasma VL. The Samba sample preparation chemistry was adapted to use a leukodepleted WB sample for VL monitoring using the point-of-care Samba-1 semiautomated system. The clinical performance of the assay was evaluated by testing 207 consecutive venous EDTA WB samples from HIV-1-infected patients attending a CD4 testing clinic. Most patients were on antiretroviral treatment (ART), but their VL status was unknown. Compared to the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 test, the new Samba assay had a concordance of 96.5%. The use of the Samba system with a VL test for WB might contribute to HIV-1 ART management and reduce loss-to-follow-up rates in resource-limited settings.

Surface modification of polypropylene nonwovens with LDV peptidomimetics and their application in the leukodepletion of blood products.

For clinical indications and according to European standards, a depletion of the leukocytes from whole blood has to be realized before transfusion to a patient. In this study, the surface of a layer of meltblown oxygen-plasma treated polypropylene nonwoven (O(2)-PP), making part of the composition of leukodepletion filters, was modified with bioactive molecules to enhance the adhesion of leukocytes. These synthetic small molecules (called peptidomimetics) mimic the "Leu-Asp-Val" (LDV) tripeptide sequence recognized by the α(4)ß(1) integrin, a receptor expressed on leukocytes. Their activity, as ligands of the α(4)ß(1) integrin, was confirmed through cell adhesion assays. The peptidomimetics were covalently immobilized on O(2)-PP nonwoven via activation of the hydroxyl- and carboxyl-functions displayed on the polymer surface with trifluoro-triazine reagent, or were simply deposited on the O(2)-PP surface. The treated materials were characterized by X-ray photoelectron spectroscopy, wettability, and morphological analyses, before and after steam sterilization. Experimental filters composed of 10 layers of O(2)-PP nonwovens and a last layer modified with the peptidomimetics were evaluated, using whole blood filtration assays, for their leukodepletion efficiency, the recovery of red cells and platelets and the waste of blood, with an objective to design new filters fulfilling practical and medical criteria.