Hi Cheryl, There are numerous potential reasons why your viability may be low on peripheral apheresis collections. How is viability being measured? Is it the actual CD34 cells that are non viable or the pack viabilty in general which is low? Here are a few things which may be affecting your viability: Granulocyte contamination - granulocytes die within a few hours of collection, especially if packs are stored at room temperature with high cell concentrartions. Time from collection to analysis - Were the samples run fresh on these patients or stored overnight and run the next day? I am always amazed at how few people realise that most flow labs don't run 24 hours a day and often store samples overnight. If samples are stored overnight at room temperature the viabilty is reduced significantly, however if stored at 4C the viability is well maintained (usually >95%). Is viabilty measured at the time of analysis in a flow assay? If this is the case and 7-AAD or PI is used the time from sample prep, the lysing agent and storage conditions will all impact viabilty. Samples lysed in ammonium chloride must be held ON ICE for a maximum of 1 hour before flow analysis. I hope some of these ideas are helpful. Mike Michael Keeney Technical Specialist Hematology/Flow Cytometry London Health Sciences Centre 800 Commissioners Road East London, Ontario Canada N5X 2Z2 >>> "Cheryl Hardy" <chardy@medicine.umsmed.edu> 01/05/99 05:13pm >>> Could someone please give me an explanation as to why CD34 cell viability would be lower than normal on a particular patient's apheresis collection? Our FLOW unit provides a viability based upon PI staining for each CD34 it runs for our BMT transplant program, and they seldom are below 95%, as they are always run immediately upon delivery to the FLOW lab. Then, a patient came along with 70% viability one day on his apheresis collection and 84% the following day. Thoughts? Thanks in advance, Cheryl Hardy Cheryl L. Hardy, Ph.D. Associate Professor of Medicine (Research) Univ. of Mississippi School of Medicine 2500 N. State St. Jackson MS 39216 601-984-6293 601-984-5689 FAX
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