Kinetics of cell division after TK T cell infusion in lethally irradiated hosts.

(A) B6 × D2 F₁ irradiated mice received B6 BM cells supplemented with 1 × 10⁷ CFSE-labeled mature T cells from hCD4 × TK double-transgenic B6 mice. Control groups received no GCV treatment (no GCV). In treated groups, GCV treatment consisted of 5 injections that began 24 hours after grafting and were administered every 12 hours (GCV d1-3). †Time mice were killed on the experimental scheme. CFSE intensity of hCD4⁺ in CD4⁺ and CD8⁺ T cells was analyzed at different time points after grafting. Each histogram is representative of 2 mice. The peak of highest intensity on the log scale identifies the parent generation of infused donor T cells. Peaks with decreased CFSE intensity represent daughter generations that have undergone cell division. (B) The number of CD4⁺ and CD8⁺ donor T cells in spleens of grafted animals (n = 2 for each group) was evaluated at day 3½ by their expression of the hCD4 marker. The coefficient of variation of duplicates was less than 10%.