Just wanted to thank everybody who responded to my CD4/CD8 coexpression question. I received an overwhelming amount of information and I was asked by a number of people to post a short summary, so here it is: 1. Quite a few people thought that we were seeing doublets. However, this is not the case since we could not see the typical non-specific "line-like" expression in Quadrant 2. The coexpressing cells had the same intensity as the CD4+ CD8- cells but showed dim CD8 expression. 2. Some people felt this phenomenon associated with a protein in the plasma of certain patients. The cells should be washed and the coexpression will disappear. have not tried it yet since I haven't had one of those samples yet. But it makes sense, read on... 3. Some of you passed on a good reference paper (Arch pathol Lab Med. 1997; 121:381-384: CD4/CD8 coexpression) and it stated that "these cells may either represent a small population of immature lymphocytes released prematurely from the thymic gland or mature CD8 and CD4 peripheral T cells that have regained expression of the CD4 or CD8 antigen". The histograms they showed, looked exactly like the ones we saw in our lab. The author concluded that these finding are most likely associated with autoimmune diseases and do not seem to represent a malignant process. However, morphology evaluation is critical in this assessment so you don't miss a true T-cell malignancy. 4. Marc Langweiler and Gerhard Nebe-von-Caron made two excellent suggestions. Look up http://www.cyto.purdue.edu/hmarchiv/index.htm accesses the entire archive. If one tries any number of terms -such as "double positive" for example- one discovers that this very thread has been thoroughly considered in this forum several times. For instance: http://www.cyto.purdue.edu/hmarchiv/97/2821.html http://www.cyto.purdue.edu/hmarchiv/98/1011.html Search in http://flowcyt.cyto.purdue.edu/hmarchiv/ for the term cd4/8 double set radiobutton to find all words There sure is plenty of very useful information out there and I would like to put a "bug" into the ear of those wonderful organizers of various flow cytometry meetings. Could you include a session in which you instruct people how to access the important flow info, especially for clinical data. I am not sure about the rest of you but I certainly could use it. Working in a clinical lab, I have to be able to get to the relevant info fast. For the most part I start to search on something and then just get frustrated because I don't know enough how to do it and where to look. Well, on that note, thanks again for all your time and information and let me see if I can find the send button ...
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