After allogeneic hematopoietic stem cell transplantation (HSCT), patients are repetitively vaccinated to reduce the risk of infection caused by the immune deficiency following allogeneic HSCT. By the vaccination of transplanted patients, the humoral memory function can be restored in the majority of cases. It is unknown, however, to what extent memory B cells derived from the donor contribute to the mobilization of antibody-secreting cells and long-term humoral memory in patients after allogeneic HSCT. We therefore analyzed patients after allogeneic HSCT for memory B cell responses 7 days after single vaccination against tetanus toxoid (TT), diphtheria toxoid (DT), pertussis toxoid (PT), Haemophilus influenzae type b (Hib), and poliovirus. Patients showed an insufficient mobilization of plasmablasts (PB) after vaccination, whereas healthy subjects (HD, n = 13) exhibited a significant increase of PB in the peripheral blood. Regarding vaccine-specific antibody-secreting PB, all HD responded against all vaccine antigens, as expected. However, only 65% of the patients responded with a measurable increase in IgG-secreting PB against TT, 65% against DT, 33% against PT, and 53% against poliovirus. Correspondingly, the antibody titers on day 7 after vaccination did not increase in patients. A significant increase of serum titers for the vaccine antigens was detectable in the majority of patients only after repetitive vaccinations. In contrast to the low mobilization of vaccine-specific PB after vaccination, a high number of PB before vaccination was detectable in patients following allogeneic HSCT. High frequencies of circulating PB correlated with the incidence of moderate/severe chronic GVHD. In summary, patients showed a weak mobilization of antigen-specific PB and an inadequate increase in antibody titers 7 days after the first vaccination. Patients with moderate or severe chronic GVHD in their history had a significantly higher percentage of IgG-secreting PB prior to vaccination. The antigen specificity of these IgG-secreting PB is currently unknown.

异基因造血干细胞移植（HSCT）后，患者应重复接种疫苗以减少异基因HSCT后免疫缺陷引起的感染风险。通过接种移植患者的疫苗，大多数情况下可以恢复体液记忆功能。然而，在异基因HSCT后，来自供体的记忆B细胞在多大程度上有助于抗体分泌细胞的动员和长期体液记忆尚不清楚。因此，我们分析了异基因HSCT后单次接种破伤风类毒素（TT），白喉类毒素（DT），百日咳类毒素（PT），流感嗜血杆菌的7天后记忆B细胞反应的情况b型（Hib）和脊髓灰质炎病毒。接种疫苗后患者显示成浆细胞（PB）的动员不足，而健康受试者（HD，n= 13）在外周血中PB显着增加。关于疫苗特异性抗体分泌型PB，所有HD对所有疫苗抗原均产生了预期的反应。但是，只有65％的患者对TT的分泌IgG的PB有明显的反应，对DT的有65％，对PT的有33％，对脊髓灰质炎病毒的有53％。相应地，患者接种后第7天的抗体滴度没有增加。仅在重复接种后，大多数患者中才检测到疫苗抗原的血清滴度显着增加。与接种疫苗后疫苗特异性PB的动员率低相反，同种异体造血干细胞移植术后的患者可检测到大量的PB疫苗。循环性PB的高频率与中/重度慢性GVHD的发生率相关。总之，患者在首次接种后7天显示出抗原特异性PB的动员能力弱，抗体效价增加不足。在病史中患有中度或重度慢性GVHD的患者在接种疫苗之前具有较高的IgG分泌PB百分比。这些分泌IgG的PB的抗原特异性目前未知。