Philippe, A significant population of lymph node dendritic cells (surface CD3 neg.) are CD8alpha pos. (formerly "lymphoid" or "interdigitating" DCs). Check it by co-staining with CD11c, MHCII and/or DEC-205. Some myeloid LNDCs are CD4+ as well, but that shouldn't be a "huge" population as you describe it. Again, check this with the murine DC markers CD11c & MHCII. (Check out: B. Salomon et al., J Imm.1998, Vol.160, 708-717). But first make sure of course that you don't get any fragments of thymus by mistake. That shouldn't be a problem when you're extracting the (largest) LN which is down right to the trachea, just above the right main bronchus. It gets more tricky when you're extracting the parathymic LN (which also drain the airways to some extent): be sure to get the "beady" looking pair of parathymic LN and not a piece from the "blobby" white thymus. Hope this'll help you. Karim "Dr. Philippe Stock" wrote: > Hello,I am pretty much a FACS beginner. I have a question, which > nobody has been able to answer so far.Every time I do a FACS scan from > peribronchial lymph nodes (naive BALB/c mice) and stain it for cd3, > cd4 and cd8 cells I see a huge population of cd4pos/cd3neg cells, as > well as cd8pos/cd3neg cells. Does anybody know what types of cells > these are?I have to admit that isolating PBLN from naive mice is > rather tricky, usually leaving me with extracting the entire hilus and > meshing that. Could these cells derive from Thymus (which I am pretty > sure to extract beforehand) or from oesophagus?Thank you very much,Ph. > Stock
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