Mast Cell Irradiation/Chemotherapy Viability Assay

Viable mast cells were counted by hemacytometer via trypan blue exclusion and plated at 1e6/ml, then exposed to 8.5 or 20 Gy single-dose radiation from a cesium source or chemotherapeutic agents. Busulfan and cyclophosphamide were purchased from Cayman Chemicals (14843 and 13849, Ann Arbor, MI) and resuspended in DMSO. Drugging time and conditions were chosen based on clinical usage where cells were drugged with 800 ng/ml busulfan and/or 30 ug/ml cyclophosphamide, which corresponded to steady-state serum levels of the drug during clinical utilization (15). Cells were approximately 98% viable prior to irradiation. Every 24 h, cells were counted and assessed for viability by trypan blue exclusion out to 96 h post-irradiation or 72 h post-drugging.