At day 78 after semiallogeneic BMT, donor T cells display a diversified repertoire in GCV-treated thymectomized recipients.

(A) At day 78, Vβ usage was determined by flow cytometry in mCD4⁺- and mCD8⁺-gated subsets using a series of 7 monoclonal antibodies covering approximately two thirds of the T-cell repertoire. Results are given as mean ± SEM for both the semiallogeneic BMT group (▪, n = 9) and a series of donor T cells before infusion (■, n = 5). (B) Diversity of the T-cell repertoire was determined in the spleen by analyzing the distribution of TCRβ CDR3 transcript lengths (immunoscope method16 17). Peaks were separated by a 3-nucleotide length, corresponding to in-frame transcripts. Representative data are shown for 3 of 7 thymectomized mice from the semiallogeneic BMT group treated by GCV (day 78, black), compared to the Gaussian-like distribution of donor T cells before infusion (white) and to a syngeneic BMT group of thymectomized mice treated by GCV (day 90, gray).