ALL STEM CELLS

Accepted 16 July 2007

http://www.ncbi.nlm.nih.gov/pubmed/17652524

The utilization of cryopreserved peripheral blood mononuclear cells (PBMC) for immunologic assays has recently increased. These cells are particularly useful in clinical trials with low end-point frequencies, because they allow the performance of assays after the complete identification of the end points (1,8). Cryopreserved PBMC can be assayed in batches, avoiding inter- and intralaboratory variabilities when they represent potential confounders (6).
The use of cryopreserved PBMC in immunological assays poses challenges, including the availability of adequate equipment and the need for technical proficiency. Assays must be adapted and validated for the use of cryopreserved PBMC, and the quality of the frozen cells has to be monitored to ensure reliable results in functional and phenotypic assays. We have previously shown that the results of functional assays are strictly dependent on the viability of the cryopreserved PBMC (9), such that 70% viability compromises lymphoproliferative responses to antigens and mitogens. PBMC with viability of 70% are also suitable for cytokine production studies, flow cytometric analyses, and immunomagnetic cell separation (4, 5, 7, 9). While cell recovery does not interfere with the results of immunologic assays, the recovery of only a small proportion of cells may preclude assay performance altogether. Based on
these observations, cryopreservation quality assurance (QA) programs must monitor the viability and recovery of cryopreserved PBMC. We report here on an effort to assess and improve the ability of seven Pediatric AIDS Clinical Trials
Group (PACTG) sites in Brazil to cryopreserve viable PBMC.



http://www.ncbi.nlm.nih.gov/pubmed/17652524