Background/Case Studies: The Monocyte Monolayer Assay (MMA) is an In vitro assay that is used for research to predict the clinical significance of the antibody(ies) that is demonstrating in a patient’s plasma or serum. The assay predicts red blood cell (RBC) transfusion outcomes for patients with the use of Peripheral Blood Mononuclear Cells (PBMCs), which are composed of monocytes and lymphocytes cells. The PBMC source for MMA testing is usually obtained fresh at the time of testing. With the increase usage of this assay, it would be beneficial to have a frozen supply of PBMCs at the time of testing to maximize technical and testing time and reduce variability. This study will evaluate how long PBMCs remain viable after cryopreservation.
Study
Design/Methods: Obtain PBMCs from 4 source leukocyte products from whole blood donations and cryopreserve them at -80˚C for future use. Determine the percent viable by staining the thawed PBMCs with trypan blue stain. With use of a hemocytometer, count the deep blue stained PMBCs and the un-stained PBMCs. The percentage of viable, deep blue stained, PBMCs is acceptable if > 90%. The stability of cryopreserved monocytes will be measured weekly for the first month, monthly for up to a year, quarterly after year two and semi-annually thereafter. An antibody source (Anti-D) would be used as the positive quality control (QC), aliquoted, and frozen at -80˚C. All four PBMCs sources will be tested independently using a pooled R1R1 and R2R2 RBC. The length of time cryopreserved PBMCs can be used will be determined once PBMCs are no longer acceptable.
Results/Findings: Table 1. Percent Viability
Conclusions: Since the performance failed to meet acceptable criteria after the 6 months for the initial stability testing, there wasn’t a need to continue quarterly and semi-annual testing. All PBMC sources obtained satisfactory viability results for months 1-6. Therefore, the cryopreserved PBMCs can be used for MMA testing for up to six months after date of frozen when stored at -80˚C.
