Clonal analysis of secondary transplanted SRCs. (A) Study design for clonal analysis of secondary grafts. 34 indicates CD34⁺ stem/progenitor cells; M, CD33⁺ myeloid lineage cells; B, CD19⁺ B-lymphoid lineage cells; T, CD3⁺ (spleen) or CD4/CD8 double-positive (thymus) T-lymphoid lineage cells. (B) Relative frequencies of each clone type detected in paired secondary transplanted recipients. Data represent mean ± SD of 3 independent experiments. *P < .01 relative to other type of clones. (C) The proportion of clones detected in CD34⁺ cells is shown. A total of 43 clones in 3 independent experiments were analyzed. Gray bars represent the clones detected in CD34⁺ cells. Black bars represent the clones not detected in CD34⁺ cells. *P < .01 relative to MTB clones found in primary recipients (shown in Figure 1E). (D) The proportion of MTB clones found in CD34⁺ cells of paired secondary recipients. A total of 27 clones in 3 independent experiments were analyzed. Notation of the left vertical axis: +/+, MTB-MTB clone pairs were detected in CD34⁺ cells of both secondary recipient pairs; +/–, MTB-MTB clone pairs were detected in the CD34⁺ cells of 1 of the 2 secondary recipient pairs; and –/–, MTB-MTB clone pairs were not detected in the CD34⁺ cells of either secondary recipient pairs. (E) Relative clone size of individual clones in each MTB-MTB clone pairs in CD34⁺ stem cell pool found in paired secondary recipient. The relative clone size of individual clones in 11 MTB-MTB clone pairs detected in CD34⁺ cells of both secondary recipients was examined by RQ-PCR. The relative clone size of individual clones in each MTB-MTB pair is expressed as the proportion of one clone relative to the other clone. The MTB-MTB clone pairs no. 15-3 and no. 19-7 that was detected in the CD34⁺ cells of only 1 of the 2 secondary recipient pairs were used as experimental control and demonstrated complete skewing to either one recipient.