Red blood cell deformability in patients with human immunodeficiency virus infection

Red blood cell (RBC) deformability is a major determinant of the ability of the RBC to pass repeatedly through the microcirculation. A decrease in RBC deformability leads to tissue perfusion and organ dysfunction. The purpose of this study was to measure the rigidity of RBCs from human immunodeficiency virus (HIV) seropositive individuals and investigate its relation to immune status and viral load. A filtration method based on the initial flow rate principle was used to determine the index of rigidity (IR) of 53 samples from HIV patients and 53 healthy individuals. The mean IR was significantly increased in patients with HIV compared to healthy individuals (P < 0.01). IR was inversely correlated with current CD4+ T-lymphocyte counts (P < 0.0001). High CD4 cell counts (>200 cells/microl) are related to low IR values, independently of the viral load (VL). No differences in rigidity were noted between the VL groups, although there was a trend towards an increased IR in patients with high VL within the group of CD4<200. RBC deformability is decreased in HIV disease, in a degree mainly related to CD4 depletion. Further studies are needed to elucidate the underlying mechanisms and the role of VL in highly immunocompromised HIV patients.