Migration and expansion of donor T cells in the lymph nodes occurs independently of non-T donor splenocytes and vice versa. (A) Peyer patch. (B) Inguinal node. B10.BR mice (for allogeneic studies) or C57BL/6 mice (for syngeneic studies) were lethally irradiated and given C57BL/6 BM with either whole splenocytes, TCD splenocytes, or purified T cells from eGFP Tg C57BL/6 mice. TCD splenocytes homed to the B-cell and myeloid areas (cortical lymphoid nodules), whereas the T cells homed to the T-cell zone (deep paracortex). In the allogeneic setting, donor T cells expanded 48 to 72 hours after infusion. Tissues from 1 of 3 representative mice from each time point per group are shown. Stereomicroscope was set to 10.0 × zoom factor with a 0.63 × transfer lens. (C) Confocal microscopy of lymph node cryosections costained with anti-eGFP antibody (red) and the indicated phenotypic marker (blue). Costained cells are depicted as violet-purple. On the left are nodes taken 24 and 72 hours after BMT of allogeneic BM and eGFP Tg whole splenocytes. On the right are nodes taken 24 and 72 hours after BMT of allogeneic BM and eGFP Tg TCD splenocytes. The images are consistent with the data in Figure 5A and 5B showing that donor cells localized early, at 24 hours after transplantation to the lymphoid follicles, consisted predominantly of B cells (CD19) and fewer myeloid cells (CD11b). eGFP Tg T cells (CD4 and CD8) are predominantly in the paracortex and were more apparent at 72 hours after transplantation. Original magnification × 200.