RBC fate is not determined by changes to target cells. (A) Naive RBCs were labeled with CSFE (•) or biotin (○) and adoptively transferred into infected semi-immune mice on day 2 or day 4 after patency, respectively. Survival was monitored by flow cytometry and is expressed as a percentage change in total number of transferred RBCs; n = 6 ± SEM. The inset shows the percentage change in Hb (▴) in semi-immune mice over the same period of days after patency. (B) Comparison of rate of the survival of naive CSFE-labeled (•), naive biotin-labeled (○), and resident host biotin-labeled (▪) cells in semi-immune mice. Values are expressed as percentage change in the total number of cells present from day 4 after patency (100%). n = 6 ± SEM. (C) RBCs from (i) noninfected naive mice, (ii) nonanemic semi-immune mice on the day of patency, and (iii) anemic semi-immune mice on day 4 after patency were biotinylated in vivo and adoptively transferred into naive recipients. Survival was monitored by flow cytometry. Plots show circulating RBC populations in the recipients on the day of transfer (day 0) and day 6 after transfer. Survival rate values show the mean percentage survival of cells from each donor group on day 6 after transfer. n = 5 ± SEM.