THE Q-PREP SYSTEM - EFFECTS ON THE APPARENT EXPRESSION OF LEUKOCYTE CELL-SURFACE ANTIGENS

To facilitate the analysis of immunolabelled peripheral blood or bone marrow leucocytes by flow cytometry, a number of reagents are availabl e commercially that lyse erythrocytes and fix leucocytes. This study h as investigated the effect on antibody-labelled whole blood of the Q-P rep procedure, in which erythrocytes are lysed with formic acid, and l eucocytes are fixed with formaldehyde. Whole blood samples were labell ed with the nuclear dye LDS-751 and with antibodies to HLA-DR or belon ging to CD2, CD3, CD4, CD7, CD8, CD10, CD13, CD14, CD19, CD20, CD29, C D33, CD45, CD45RA, CD56, and CD62L (TQ-1) that were directly conjugate d to either phycoerythrin (PE) and/or fluorescein isothiocyanate (FITC ). Leucocytes were analysed by flow cytometry either in unfixed, unlys ed whole blood (15) or after preparation using the Q-Prep system. The binding of eight antibodies, CD19-FITC, CD2-PE, CD3-PE, CD4-PE, CD19-P E, CD29-PE, CD45RA-PE, and CD56-PE, to the surface of lymphocytes was reduced, resulting in significant changes (P < 0.05) in the percentage s of cells that stained positively and/or their mean molecules of equi valent fluorochrome (MEF). Further analysis revealed that this was due to the formic acid used during the erythrocyte lysis stage. (C) 1997 Wiley-Liss, Inc.