Conversion from mixed to full donor chimerism without GVHD following DLI.

(A) DLI led to conversion from mixed to full donor hematopoietic chimerism. Peripheral blood multilineage donor chimerism was determined with lineage-specific markers using H2-D^d–specific mAb 34-2-12 in 2-color flow cytometry. Animals were reconstituted either with TCD B10.A BM alone (no DLI, ▴, n = 4) or with a mixture of 15 × 10⁶ TCD B10.A plus 5 × 10⁶ B6 BM (no DLI, ▪, n = 4). Spleen cells (3 × 10⁷ B10.A) were administered to additional groups of mixed and full chimeras on day 56 after BMT. Conversion to full donor chimerism was observed in all mixed chimeras receiving DLI (■, n = 4). Full chimeras remained full donor in all lineages after DLI (▵, n = 5), and T cells converted to full donor chimerism as well. Mean percentage donor chimerism ± SD from one representative experiment is presented. The arrow denotes the time of DLI administration. One representative result of 4 similar experiments is shown. (B) DLI does not cause GVHD. Spleen cells (3 × 10⁷ B10.A) were administered on day 56 after BMT to mixed and full chimeras. DLI recipients (full chimeras ▵, n = 4; mixed chimeras ■, n = 4) had weight curves similar to those of non-DLI recipients (full chimeras ▴, n = 4; mixed chimeras ▪, n = 5) and did not show clinical signs of GVHD. Results from one representative experiment are shown.