Central nervous system (CNS) complications have been described in patients undergoing allogeneic hematopoietic cell transplantation (alloHCT). Cerebrospinal fluid (CSF) analysis is included in the diagnostic workup in patients with neurological symptoms after alloHCT. CSF donor-recipient chimerism analysis usually is not used to evaluate patients with neurological complications after alloHCT. To assess the potential contribution of CSF donor-recipient chimerism in patients
with neurological complications, we analyzed 85 CSF samples from 50 patients with neurological complications after alloHCT. After alloHCT, 21 patients showed the presence of recipient-derived DNA. In 13 of these patients, recurrence of the underlying disease was detected in CSF. There was a moderate correlation between the recipient DNA percentage as detected by short tandem repeat (STR) amplification and the cell concentration in CSF (Spearmann r: 0.66 P=0.004). The percentage of cells with immunophenotypic abnormalities from patients relapsing in the CNS detected by flow cytometry showed a strong correlation with the percentage of recipient-derived DNA in CSF assessed by STR analysis (Spearmann r: 0.83 P=0.0008). Donor-recipient chimerism analysis in CSF in patients with neurological symptoms after alloHCT is a practical, feasible and useful complementary method to the already established methodologies included in the diagnostic workup.