AIM: To investigate the ability of Chinese cobra snake venom-metalloproteinase(MT) to induce the histamine release from human mast cells and its potential mechanisms.METHODS: MT was purified from the snake venom by using heparin agarose and Superdex75 chromatography.Mast cells were dispersed from human lung, colon and tonsil tissues after digestion with collagenase and hyaluronidase.The dispersed mast cells were then challenged with MT,stimulus and control in LP4 tubes for 15 min at 37 ℃.A glass fibre-based fluorometric assay was used to measure histamine in the supernatants of dispersed mast cells.RESULTS: MT induced a dose-dependent release of histamine from human colon,lung and tonsil mast cells.As low as 0.03(mg/L) of MT was able to stimulate significant histamine release from human colon mast cells,but a minimum of 0.3 or 30 mg/L of MT was required to stimulate a similar level of histamine release from lung or tonsil mast cells,respectively.The release of histamine from colon and lung mast cells in response to MT was maximized at 12 min following the addition of the stimulus.This was quite different from the picture of the peak histamine release from tonsil mast cells,in which histamine release was maximized at 8 min following the addition of MT.Pretreatment of cells with metabolic inhibitors and pertussis toxin reduced dramatically histamine release from human colon,lung and tonsil mast cells by MT.In exogenous Ca~(2+) and Mg~(2+) free experiments,the release of histamine induced by MT was significantly decreased.CONCLUSION: Cobra snake venom MT induces human mast cells to release histamine through a G-protein-related mechanism,which may contribute to the pathogenesis of venomous snake bite.

Objective: To investigate the clinical significance of minimal residual disease (MRD) monitoring by using WT1 gene and flow cytometry (FCM) in patients with myelodysplastic syndrome (MDS) who receiving allogeneic stem cell transplantation (allo-HSCT). Methods: WT1 gene and MDS-related abnormal immunophenotype were examined by real-time quantitative polymerase chain reaction (RQ-PCR) and FCM, respectively. The bone marrow samples were collected from patients with MDS who received allo-HSCT from Feb, 2011 to Oct, 2015 in Peking University People’s Hospital before and after transplantation. Results: Among 92 MDS patients, 40 (48.2%) patients were positive for WT1 (WT1⁺) and 9 (10.8%) patients were positive for flow cytometry (FCM⁺). 27 patients (29.3%) met the criteria of our combinative standard, MRDco (MRDco⁺). Only FCM⁺ post-transplant (P<0.001) and MRDco⁺ (P=0.017) were associated with relapse. The cumulative incidence of relapse (CIR) at 2 years were 66.7% and 1.2% (P<0.001) in FCM⁺ and FCM^- groups. MRDco⁺ group had a 2-year CIR of 23.0% while MRDco^- group had a 2-year CIR of 1.6% (P=0.004). The specificity of post-transplant WT1, FCM and MRDco to predict relapse was 59.0%, 96.4% and 74.7%, respectively. The sensitivity of these three MRD parameters to predict relapse was 66.7%. Conclusion Post-transplant FCM and MRDco are useful tools to monitor MRD for MDS after transplantation. The preemptive intervention based on MRDco is able to reduce the relapse rate.