Flow cytometric three-color determination of CD4 T-lymphocytes on blood specimens from AIDS patients who have a large number of contaminating non-lymphocytes.

A three-color flow cytometric determination of CD4 T-lymphocytes on whole blood specimens from AIDS patients which contain a high proportion of non-lymphocyte elements is described. Peripheral blood cells were stained by a three-color method using monoclonal antibodies conjugated respectively with fluorescein isothiocyanate (FITC)-CD3, phycoerythrin (PE)-CD4 and peridinin chlorophyll protein (PerCP)-CD45. CD45 stains all leukocytes with the highest fluorescence expression of CD45 antigen in lymphocytes. By combining light scatter with CD45 in the fluorescence 3 (FL3) channel, a light scattering window can be drawn to include almost all bright CD45 lymphocytes. This live gate of lymphocytes was then acquired and analysed simultaneously using other irrelevant two-color (FITC/PE) antibodies of CD3 and CD4 in the FITC and PE channels, respectively. This method is easy and straightforward, and gives successful analysis of CD4 T-lymphocytes in AIDS blood specimens contaminated with an unusually large number of non-lymphocytic cells.