HPA Frequencies in the Syrian Population.

BACKGROUND: Exposure to allogenic Human Platelet Antigens (HPAs) can lead to antibody formation causing different immunological reactions. Frequencies of common HPA antigens differ between ethnic groups and should be known to calculate potential alloimmunization risk. Syrian refugees are the largest group of applicants for asylum in Germany in 2017. However, no study on HPA antigen frequencies in the Syrian population exists. METHODS: DNA from blood samples of 96 volunteers with Syrian origin was isolated. The genotype of HPA-1, -2, -3, -4, -5, -6, -9, and -15 was determined using a commercialized polymerase chain reaction kit with sequence-specific primers (SSP-PCR). Data were compared with data formerly obtained from the German population and diverse other studies. RESULTS: In Syrian population, the gene frequencies of HPA-1a/1b, -2a/2b, -3a/3b, -4a/4b, -5a/5b, -6a/6b, -9a/9b, and -15a/15b were 0.837/0.163, 0.875/0.125, 0.630/0.370, 1.000/0.000, 0.837/0.130, 1.000/0.000, 1.000/0.000, and 0.457/0.543, respectively. CONCLUSIONS: There are no significant differences between HPA antigen frequencies in the Syrian and German population. Therefore, we do not see a need for special precaution in the selection of blood products or in pregnancy of interethnic couples with regard to HPA.

Navigating preemptive and therapeutic donor lymphocyte infusions in advanced myeloid malignancies by high-sensitivity chimerism analysis.

Preemptive and therapeutic donor lymphocyte infusions (preDLI and tDLI) are widely used in relapsing and relapsed hematopoietic malignancies after allogeneic stem cell transplantation (alloSCT) to enhance the graft-versus-malignancy effect. However, in advanced myeloid malignancies, long-term survival after preDLI and tDLI remains low, reflecting our inability to master the double-edged sword of alloreactivity, balancing anti-neoplastic activity versus graft-versus-host disease (GvHD). We previously evaluated a quantitative PCR-based high-sensitivity chimerism (hs-chimerism) based on insertion/deletion polymorphisms instead of short tandem repeats, where increasing host chimerism in peripheral blood predicts relapse more than a month before clinical diagnosis, and declining host chimerism signals anti-host alloreactivity. Here we report 32 consecutive patients with advanced myeloid malignancies receiving preDLI or tDLI "navigated" by hs-chimerism ("navigated DLI"). We compared them to a historical cohort of 110 consecutive preDLI or tDLI recipients, prior to implementation of hs-chimerism at our institution ("controls"). Both groups were comparable regarding age, gender, conditioning, donor type, and time to DLI. With longer median follow-up of the navigated DLI group (8.5 versus 5 months), their landmark overall (64%) and disease-free survival (62%) at 2 years from first DLI compared favorably with controls (23% and 21%, respectively). Improved survival of navigated DLI was due to both reduced relapse incidence (38% versus 60%) and non-relapse mortality (17% versus 44%) at 2 years. Early relapse prediction by hs-chimerism allowed a preemptive approach in 28% of navigated DLI versus 7% in controls. Our results confirm hs-chimerism as a highly valuable tool for monitoring and steering immune interventions after alloSCT.