Removal of Trypanosoma cruzi by white cell-reduction filters: an electronmicroscopic study.

White cell (WBC)-reduction filters have been shown to be effective in removing infectious agents from infected blood products. In this study, the mechanisms of Trypanosoma cruzi (T. cruzi) retention by WBC-reduction filters were assessed. Human packed red blood cell (PRBC) and platelet concentrate (PC) samples were contaminated with T. cruzi organisms (Y strain; 3.4 x 10(6)/ml), and then filtered using WBC-reduction experimental filters that provided about 3 log10 WBC removal. Transmission electron microscopy sections showed that T. cruzi parasites were removed from contaminated PRBC and PC samples primarily by mechanical mechanism without interacting with filter fibers or blood cells. In addition, we found that T. cruzi parasites were also removed by a direct fiber adhesion. These data indicate that T. cruzi parasites are removed from infected blood not only by mechanical mechanism but also by biological mechanism probably mediated by parasite surface proteins.