I have combined all of the responses to my Cyto Chex queary and have included those responses (with names removed) below. In summary, most people responded positively but there were two people who have had poor results with this product. There seems to be conflicting results regarding use of this product with whole blood. My own testing, while progressing slowly is encouraging. I have tried it on a positive B-ALL bone marrow with no differences one week later. I have also tried it on a CSF specimen and the specimen held in Cytochex looked better than the one we processed fresh. I thank everyone for their detailed experiences with the product and hope that this turns out to be the answer to my weekend prayers!! I am also interested in further experiences with this reagent. Abby Kelliher Clinical Flow cytometry Lab Mass. General Hospital Boston, MA 02114 Positives: ---------------------------------------------------------------------------- -------------------------- We have used Cyto Chex over weekends on blood and it works well. ---------------------------------------------------------------------------- -------------------------- I usually don't keep blood or bone marrow specimens for a week before flow analysis (usually it's 2-3 days, due to weekends and my being off one day for working the weekend in the coag section of our lab), but the vast majority of the time, I get good results with keeping blood/bone marrow samples in Cyto-Chex--as long as we get the specimen into the Cyto-Chex the same day that it has been obtained. I get VERY good results with keeping tissues in Cyto-Chex, as long as I disaggregate the tissue the same day that it has been received by the pathologist assistants. I think the occasional junky-looking specimens have more to do with the specimen itself, not the Cyto-Chex, per se. ---------------------------------------------------------------------------- -------------------------- We have been using Cytochex for a couple of months now and are pretty happy with it. For the most part we get very good light scatter and Ag expression. We use it on late Friday afternoon specimens and use it only on non-bloody specimens. I would not recommend it for whole blood since we have had some problems with it too (as one person described it today on this list). If you want to do bone marrows or bloody specimens, you need to lyse it first and then store it in Cytochex. The only problems we have encountered so far, are: 1. DNA ploidy is often near-diploid even on benign samples after Cytochex storage. 2. CD 10 expression seems to be often non-specifically positive. But if you compare against your internal negatives, you are able to determine whether the positivity is true or non-specific. 3. Problems with peripheral blood as described. We really try to only use it when it is too late on Friday to analyze but it is not a stat specimen. Over all, it is not the perfect solution but pretty close! ---------------------------------------------------------------------------- -------------------------- We have been using the cyto chex for over a year, but our validation shows a good correlation up to 4 days, we used over weekends or holidays. Do not check viability by PI or 7AAD after cyto chex some permeabilization is present. ---------------------------------------------------------------------------- -------------------------- I have carried out some stability work on cytochex, but it was limited to whole blood and ORTHO TRIO reagent i.e CD3/4/8/16/19. We tested over an eight day period at room temp and 4degC. and the results were very good. If I remember rightly, the manufacturers state that the sample should be viable up to 7 days at 4 deg C for both transport and storage. The only issue to keep in mind is obtaining accurate dilutions for absolute counts. ---------------------------------------------------------------------------- -------------------------- I also have had excellent experience with this product. Although I was one of the original "testers" of this product I have taken it further and used it in my lab for my own purposes. For example, I stimulated normal peripheral blood with CD2/2R to obtain high expression of CD69. When the blood is put in Cyto-Chex the specimen can be used as a positive control In our activation assays for at least one week with no loss of antigen expression. We're pursuing other uses for this great product. Also , when we need a "normal" control (fresh blood) we draw only on Monday, put the blood in Cyto-Chex and use it the rest of the week so we don't have to draw someone daily. I hope you keep experimenting with other uses for this great product. I have nothing but good to say about it. ---------------------------------------------------------------------------- -------------------------- We have looked very extensively to the Streck reagents: -Platelet Chex (unfortunately discontinued) -CD Chex -CD Chex Plus -Cyto Chex This Streck company has some great products. We evaluated their controls and stabilizers for our quantitative flow cytometry application kits. You must know that quantitative flow is not very forgiven and we found great performances for these products on various measurements. It did not work for everything. ---------------------------------------------------------------------------- -------------------------- Negatives: ---------------------------------------------------------------------------- -------------------------- I tried it out in my lab in Massachusetts to permit fedexing samples from the South. A single sample of human blood (mine) was treated with CytoChex on day zero and then analyzed daily for the next 4 days. The results of CD4+ and CD8+ were significantly different on day 1 and subsequent days. As a result, despite our great hopes according to claims made, we did not adopt its use. ---------------------------------------------------------------------------- -------------------------- I hate to comment because I haven't finished my own evaluations. But, it's not at the top of my list of to do's because I wasn't overly pleased with the initial comparison data. I did have better results for subsets than the one who got varying subset values on days 2, 3, 4. We use a CD45 v. Side gating strategy for subsets and got comparable percentages on days 2 and 3 - I didn't test beyond that. The scatter, however, looks pretty bad as grans don't seem to hold up well. While it's true that that is of no great consequence with my particular gating strategy, it could lead to a very messy specimen for those using light scatter gating, since the grans frequently fall into the gated area. And it just looks bad - I hate reporting out stuff that is so obviously aged, even if it has been validated on some other bunch of samples. Also, we tried Cytochex on some lymph node and bone marrow specimens. Same story - ratty looking cells. Worse, though, was that it appeared that the surface light chain expression was undemonstrable after Cytochex storage of the single cell specimen preparations. If I can't demonstrate clonality if present, I might as well not run the specimen. I knew that there was some literature out there using this preservation method, so asked my new Streck salesman for it. He zipped it right over to me - you should ask them for it via fax - or I'll send it to you if you want. What the paper _apparently_ says (ok, I haven't read it all the way through yet, myself, but a co-worker reported the findings to me) is that the reagent would keep the neutrophils from upregulating or otherwise changing the CD11b status of the specimen. The pictures I did look at(!). It looked to me like a large part of the specimen had turned to debris after three or however many days. While it may be so that the percentage of CD11b on the grans was comparable to that of the original test, I don't see how the measurement is even valid after losing a large part of the population. So that's my take on it. I haven't given up, but really don't see using it. I purchased a ton of it, too, expecting that it would be just what I needed (the lab's closed on Sat/Sun).
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