A simple method to optimize peripheral blood mononuclear cell preparation from cynomolgus monkeys and improve mixed lymphocyte reactions

Introduction: The standard Ficoll–Hypaque method used to isolate peripheral blood mononuclear cells (PBMC) gives very variable results when used with cynomolgus monkey blood. We have improved the method by using special cell processing tubes (CP-tubes), originally developed for clinical use. Methods: Blood samples were collected from cynomolgus monkeys and processed for PBMC preparation using either the classical Ficoll–Hypaque method or CP-tubes following various centrifugation protocols. The preparations were compared according to their cellular content as well as their response in the mixed lymphocyte reaction (MLR). Results: Good PBMC separation was achieved in >90% of samples by centrifugation of blood samples in CP-tubes for 40–45 min at 1650× g and 20 °C. For the remaining samples, poor PBMC separation was probably due to low corpuscular hemoglobin concentrations (