AUTOMATED CELL COUNT IN FLOW-CYTOMETRY - A VALUABLE TOOL TO ASSESS CD4 ABSOLUTE LEVELS IN PERIPHERAL-BLOOD

The enumeration of lymphocyte subsets in absolute counts has long reli ed on, different methods applied separately to whole blood cell count, lymphocyte differential appreciation, and flow cytometric evaluation of lymphocyte subsets percentages. The development of multicolor label ing methods inflow cytometry now allows a more homogeneous appreciatio n of several cell subsets among gated lymphocytes. The use of internal calibrators, such as microbead suspensions, also permits a direct app reciation of subsets in absolute counts in a single-platform method. T hese methods were compared with a traditional multiplatform method of assessing absolute counts of lymphocyte subsets in a pilot study in wh ich all manipulations were performed by 1 person and in a full-scale l arger study performed in the normal working conditions of a hospital l aboratory. Microspheres seem to be a reliable tool to perform absolute count enumeration inflow cytometry, but several precautions in the sa mple preparation and flow cytometric analysis are required.