HbS May Have an Immunoregulatory Effect on T Cells as well as Antigen Presenting Cells (APCs). Reprinted from Cell, Volume 145, Issue 3; Ferreira A, Marguti I, Bechmann I, et al. Sickle hemoglobin confers tolerance to Plasmodium infection, 398-409, Copyright (2011), with permission from Elsevier.