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The recent advances in myeloma treatment result in significantly better outcomes, defined as increased progression free survival (PFS) and overall survival (OS). Since there is a proven correlation between the extend of response and prolonged survival, there is an urgent need for highly sensitive assays for the detection of minimal residual disease (MRD). Next generation flow cytometry has become a valuable approach for sensitive evaluation of the depth of complete response (CR). Here, we report the diagnostic performance and validation results of a single-tube 9-color panel assay. The validation design included intra-assay analysis measuring accuracy, inter-assay analysis estimating method’s linearity and precision and inter-assay analysis evaluating repeatability. Furthermore, in inter-operator analysis assessed the comparability of the result analysis of different operators. Staining stability was evaluated in age-of-stain experiments. Our validation results show that a reliable detection of residual myeloma cells is feasible to a detection level of 10−5 with a single-tube assay for a variety of materials (peripheral blood, bone marrow and stem cell apheresis). This study establishes highly sensitive, fully standardized approach for MRD detection in myeloma that is ready for implementation in routine diagnostic laboratories.

Patients with allogeneic stem cell transplantation (SCT) have a high risk of invasive fungal infections (IFIs) even after neutrophil regeneration. Immunological aspects might play a very important role in the IFI development in these patients. Some data are available supporting the identification of high-risk patients with IFI for example patients receiving stem cells from TLR4 haplotype S4 positive donors. Key defense mechanisms against IFI include the activation of neutrophils, the phagocytosis of germinating conidia by dendritic cells, and the fight of the cells of the innate immunity such as monocytes and natural killer cells against germlings and hyphae. Furthermore, immunosuppressive drugs interact with immune effector cells influencing the specific fungal immune defense and antimycotic drugs might interact with immune response. Based on the current knowledge on immunological mechanism in Aspergillus fumigatus, the first approaches of an immunotherapy using human T cells are in development. This might be an option for the future of aspergillosis patients having a poor prognosis with conventional treatment.

Background: After allogeneic SCT, NK cell mediated cytotoxicity is an important defense mechanism against residual tumor cells and viral infections. Using a novel flow cytometric assay, which detects the lytic granule membrane protein CD107a as a marker for NK cell degranulation, we investigated the effect of in vivo T cell depletion and the type of conditioning on NK cell function in the early phase after transplantation. Methods: At day +30 and day +90 after allogeneic SCT with regular (n=14) and dose reduced conditioning (n=8), PBMCs were coincubated at 37°C for 3 h with the NK sensitive cell line HL60. 20μl of PE-Cy5 conjugated anti-CD107a monoclonal antibody (moAb) was added to each tube containing 400μl effector/target cell suspension (2x106 cells, E:T ratio 1:1) prior to incubation. After 1 hour, 10μl of monensin (2mM) was added. After incubation for 3 hours, the cells were stained with conjugated moAb (CD56, CD16, CD3) for flow cytometry. The percentage of CD107a expressing NK cells was assessed and the absolute number of degranulating NK cells /μl was calculated. Results were compared to values from 15 healthy controls. Results: Twenty two patients (pts.) were investigated. Fourteen pts. received a conventional conditioning regimen and eight a reduced intensity conditioning. T cell depletion was applied in 15/22 pts. (ATG n=12, alemtuzumab n=2, 1 OKT-3 n=1). The type of donor included MRD (n=7) and MUD (n=15). At day +30, the proportion of NK cells with cytotoxic activity (indicated by the mean percentage of degranulating CD107a+/CD56+ cells) was significantly reduced as compared to normal donors (2.6% vs. 5.6%, p Conclusion: Although the proportion of NK cells is increased after allogeneic SCT, our data suggest that the cytotoxic activity of these cells is considerably reduced. The absolute number of NK cells with cytotoxic activity is significantly higher after reduced intensity conditioning which may contribute to the effectiveness of these regimens. Antibody induced in vivo T cell depletion with ATG showed no impact on NK cell activity during the first two months post SCT.