Microchimerism in peripheral blood and CD34⁺ cells in a patient (patient 9) surveyed before and 3 months after orthotopic liver transplantation as detected by nested SSP-PCR for the HLA-DRB gene.

Donor-specific bands are indicated by an arrow. 14.* and 13.* indicate different DRB subtypes. (A) DNA sample of patient 9 (DR215 and DR3) before transplantation, used to determine the patient's chimeric state before orthotopic liver transplantation. DR17 and DR18 are both serologic splits of DR3 and they have a strong sequence homology. This causes a cross-reactivity in the nested SSP-PCR assay. DR51 is the product of the DRB5 gene; DR52 is the product of the DRB3 gene. These genes are in linkage with DR2 and DR3, respectively. Unspecific additional bands are DR13.*. (B) DNA mix containing the same sample as in panel A in 1:1 dilution with an original DNA of patient 9's liver donor (DR511). DR11 and DR12 are both serologic splits of DR5, and they have a strong sequence homology. This may cause a cross-reactivity in the nested PCR-SSP assay. (C) DNA from peripheral blood from patient 9 at 3 months after orthotopic liver transplantation. The recipient-specific band is 11, whereas the band in 103 is not specific for this donor/recipient combination. (D) DNA from bone marrow–derived CD34⁺ cells. Bands specific for the recipient are 11 and 12. No further bands can be detected.