A novel method to quantify and characterize leukemia-reactive natural killer cells in patients undergoing allogeneic hematopoietic stem cell transplantation following conventional or reduced-dose conditioning.

The antitumor activity of natural killer (NK) cells has recently been shown to be assessable at a single-cell level via flow cytometric detection of CD107a. We used this novel method to prospectively quantify and characterize tumor-reactive NK cells in patients undergoing myeloablative or nonmyeloablative conditioning and allogeneic hematopoietic stem cell transplantation (HSCT). Degranulation of NK cells in the peripheral blood of 34 patients after HSCT (day +30, day +90) was determined by evaluating CD107a expression after coincubation of the cells with tumor targets. The percentage of degranulating NK cells was higher after nonmyeloablative conditioning than after myeloablative conditioning (P<.001), indicating a higher activation state and increased antitumor activity of NK cells after nonmyeloablative conditioning. We were able to analyze NK cell subsets separately and found that CD56bright NK cells following HSCT are functionally different from CD56bright NK cells in healthy donors, as indicated by a high percentage of degranulating NK cells in response to tumor targets in patients after HSCT. The CD107a assay is a new and feasible method to quantify and characterize tumor-reactive NK cells after HSCT. Using this method, we found that NK cells had high antitumor cytotoxic activity after nonmyeloablative conditioning, which may contribute to the effectiveness of nonmyeloablative conditioning.

Secondary cutaneous aspergillosis due to Aspergillus flavus in an acute myeloid leukaemia patient following stem cell transplantation.

In a 64-year-old man suffering from hypoblastic myelodysplastic syndrome a secondary acute myeloid leukaemia developed. After induction chemotherapy with resulting partial remission he received an allogenic (related) peripheral blood stem cell transplantation conditioned with 2 Gy total body irradiation. After haematopoietic reconstitution chest pain and dyspnoea appeared. Computer tomography revealed diffuse bilateral infiltrates which were considered to be suspicious for an invasive pulmonary aspergillosis of the left upper lobe. Respiratory and circulatory insufficiency occurred. In bronchoalveolar lavage fluid Aspergillus antigen was detected. In addition, Aspergillus flavus was isolated on Sabouraud-dextrose agar. Ambisome (liposomal encapsulated amphotericin B) was applied in high dosages. On the skin of the sides and the back five livid red stained nodular lesions with haemorrhagic infarctions appeared. Pathohistologically, both in PAS (periodate acid Schiff) and Grocott-Gomori staining conglomerates of septated hyphae were detected in corium and subcutis. In addition, Aspergillus flavus grew from skin tissue. Despite antifungal treatment the patient died from Aspergillus pneumonia and generalized aspergillosis with dissemination to heart, brain, and skin.

Unrelated donor granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cell transplantation after nonmyeloablative conditioning: the effect of postgrafting mycophenolate mofetil dosing.

We previously reported results in 71 patients with advanced hematologic malignancies given HLA-matched unrelated granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cell (G-PBMC) grafts after fludarabine 90 mg/m(2), 2 Gy of total body irradiation, and postgrafting mycophenolate mofetil (MMF) 15 mg/kg twice daily and cyclosporine 6.25 mg/kg twice daily orally. Graft rejection was 15%; the cumulative probability of acute graft-versus-host disease (GVHD) was 52%. According to MMF pharmacokinetic studies, which showed a short half-life of its active metabolite, mycophenolic acid, we increased MMF dosing from 15 mg/kg twice daily to 15 mg/kg 3 times daily to increase immunosuppression and reduce the incidence of both graft rejection and acute GVHD. Among 103 patients so treated, graft rejection occurred in 5%, whereas acute GVHD remained at 53%. Outcomes were compared with results of previous G-PBMC recipients given MMF twice daily. Infection rates were slightly higher with MMF 3 times daily than with MMF twice daily. Nevertheless, 2-year nonrelapse mortality and overall and progression-free survivals were similar for MMF 3-times-daily and twice-daily patients (19%, 58%, and 49% versus 20%, 48%, and 37%, respectively). Nonmyeloablative conditioning with postgrafting cyclosporine and MMF given 3 times daily allowed 95% durable engraftment of unrelated donor G-PBMC grafts.