>There is a letter to the editor in BLOOD , September 1996, >15:88(6):23558-61 by van Vugt, MJ et al which shows that PE-CY5 >binds SPECIFICALLY to the Fc(gamma)R1 receptor (CD64). These >experiments using mouse B cells transfected with different human Fc >receptors showed that only FcR1 cells bound PE-CY5. Whole blood >showed much less binding than isolated cells. Their recommendation >was that any antibody that you are using labelled with PE-CY5 be tested >for FcR1 binding. >In our hands blocking with heat inactivated normal human AB serum will >significantly reduce the Fc binding in humans. > >Mike Keeney >London Health Sciences Centre >London Ontario Canada along the same line: Takizawa, F. Kinet, J.P. Adamczewski, M. D 1993 T Binding of Phycoerythrin and Its Conjugates to Murine Low Affinity Receptors for Immunoglobulin-G %J Journal of Immunological Methods %C PO Box 211, 1000 AE Amsterdam, Netherlands %I Elsevier Science Publishers BV %V 162 %N 2 %P 269-272 %@ 0022-1759 %K Phycoerythrin; Flow Cytometry; Fc Receptor; (Mouse); FC-RECEPTORS; MACROPHAGE %X Conjugates of R-phycoerythrin are widely used for immunohistochemistry, especially for two-color flow cytometry. Their use is however limited by their apparent tendency to bind non-specifically. Using cells transfected with cDNAs for the murine low affinity receptors for immunoglobulin G (FcgammaRII and -III) and cells naturally expressing these receptors, we demonstrate that R-phycoerythrin and its conjugates bind specifically and inhibitably to FcgammaRII and -III. Immunofluorescence stainings of cells bearing these receptors, such as macrophages, monocytes, neutrophils, mast cells, subsets of T cells, and natural killer cells, may therefore not reflect the binding of antibody to antigen, but rather the binding of R-phycoerythrin to the receptors. %W M Adamczewski, Niaid, Molec Allergy & Immunol Sect, Twinbrook II, RM 108, 12441 Parklawn Dr, Rockville, MD 20852 -- ============================================================================== Thomas Delohery |Internet: t-delohery@ski.mskcc.org Supervisor, Flow Cytometry Core Facility | Phone: (212) 639-8729 Memorial Sloan-Kettering Cancer Center | Fax: (212) 794-4019 1275 York Ave. Box 98 | New York, NY 10021 | ==============================================================================
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