Maciej, While I can't offer a clinical perspective on your finding and its significance, here is some background on CD11b/CD18: CD18 can combine with the CD11a,b or c subunits to form to form the integrins LFA-1, Mac-1 and p150,95. The CD11b/CD18 +/+ cells are expressing Mac-1, but can also have the other integrins. The CD18+/11b- cells are negative for Mac-1, but are expressing one or more of the other CD18-utilizing integrins. One of the ligands for Mac-1 is iC3b, a complement component which is of course soluble; other soluble ligands are fibrinogen and factor X. These could be one reason why staining whole blood is contraindicated. Do you know whether the patient has a leukocyte adhesion defect? I believe this is more likely to be seen with loss of CD18, where all 3 integrins are missing. CD11b is also highly expressed on CD8+ effector T lymphocytes (Hamann, D, J.Exp. Med., 1997); and you are only seeing a decrease, not an absence of CD11b+ cells. I'm sure there are other readers who can give you more in-depth info on this, but its a start. For a reference try: Larson, RS and Springer,TA (1990) Immunol. Rev. 114, 181-217. good luck, Mandy >Greetings once again, > >We have recently received a blood specimen and were asked to stain >for CD18/11b ( I love it how doctors don't explain the condition of >the patient ahead of time, so we know what to look for ) > >We found, that when compared to our NC's (N=300+ for this "tube" and >growing) this patient had less +/+ lymphoctes (~30% vs. 12%). The >expression of CD18 was not reduced - all of his leukocytes had >97%. > >A question came up: what is the significance of CD18+/CD11b- >lymphocytes? what is the significance of a decrease in the +/+ >population? > >We do not routinely do CD11a or CD11c - are these mutually exclusive? >I.e. it's either a, b or c but never any of them together? > >And finally, is the ligand for CD11b soluble and may have interfered >with our staning? > >This staining was done in whole blood (which I just found is a >no-no). > >I would appreciate if anyone could share any thoughts on this topic. > >Maciej > >__________________________________________________ >Do You Yahoo!? >Send online invitations with Yahoo! Invites. >http://invites.yahoo.com
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