Background. Fingerprint amino acid patterns within the carboxy terminus of
the latent membrane protein (LMP1) oncoprotein of Epstein-Barr virus (EBV)
allow individual strain identification at the molecular level. LMP1 is expr
essed in the tumor cells of EBV-associated posttransplant lymphomas (PTLs)
and the LMP1 genome is also identified in lymphocytes of most donors of all
ogeneic bone marrow. Therefore, LMP1 genotyping in donor lymphocytes and PT
L tumor cells, together with sex chromatin determination of tumor cells, al
lows to determine the origin of PTL tumor cells and the origin of individua
l EBV strains harboured by them.
Methods. We traced the origin of aggressive PTLs occurring in six patients
after allogeneic T cell-depleted stem cell transplantation (allo-SCT). DNA
was extracted from donor lymphocytes and PTLs of recipients and amplified w
ith LMP1-specific primers in each case. A comparative sequence analysis of
the fingerprint LMP1 region identified in donor lymphocytes and lymphoma wa
Results. One lymphoma of donor origin occurred after highly selected CD34PBSCT and contained the same LMP1 genotype as the donor lymphocytes. Three
lymphomas of recipient origin had deletions within the carboxy terminus of
LMP1, not identified in the donor strains. All lymphomas occurred in the se
tting of allo-SCT and had a rapid clinical course.
Conclusions. These results show that highly selected CD34+ PBSCT does not p
rotect against transfer of EBV positive founder cells of donor type PTL and
that, after allo-SCT, recipient type PTLs are not uncommon. Outgrowth of r
ecipient type lymphoma may be favoured by LMP1 deletion variant strains pre
sent in recipient lymphocytes.