Did you wash the cells before staining them? There is a serum protein in a subpopulation of people that causes binding of certain directly conjugated antibodies in a convincing manner. Washing before hand removes it. CD19 is pretty specific for B cells. I would want to make sure there wasn't a switch in antibodies (lab error) or artifact before coming to this conclusion. Maryalice Maryalice >We recently received a peripheral blood sample on an 80 year old gentleman >with mild leukocytosis and an absolute lymphocytosis (WBC-13,700/ul, 70% >lymphocytes). Many of the lymphocytes had the morphology of LGLs. The >lymphocytes showed expression of CD8, CD3, CD7, CD11c and CD16 without >significant expression of CD4, CD2 or CD5. The phenotype is good for the >T-cell type of LGL. Interestingly, the cells also showed relatively bright >expression of CD19. I found a couple of case reports describing similar >cases with CD20 but not with CD19. Has anyone else seen this in their >personal experience or documented in the literature? Thanks in advance for >your input. > > >Christopher S. Bee, M.D. >Medical Director, Cellular Immunology and Flow Cytometry >Wilford Hall Medical Center >Lackland AFB, Texas >(210) 292-5455 >DSN 554-5455 >christopher.bee@59mdw.whmc.af.mil Maryalice Stetler-Stevenson Director Flow Cytometry Unit Laboratory of Pathology, NCI, NIH "Learn the rules so you know how to break them properly." The Dalai Lama
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