A SIMPLE METHOD FOR THE FLOW CYTOMETRIC ANALYSIS OF INTRACELLULAR ANTIGENS IN WHOLE SMOOTH-MUSCLE CELLS - QUANTIFICATION OF CYCLIN-DEPENDENT KINASE 2

Flow cytometry has become a widely used technique for the quantitative analysis of antigens at the single cell level. In the past, several p rotocols have been published for the detection of cytoplasmic and nucl ear antigens in various cell lines, especially blood cells or cells gr owing in fluid culture. The applicability of these protocols to cells growing in a monolayer, such as smooth muscle cells (SMC) is often res tricted, although flow cytometry is of great interest in the fields of arteriosclerosis and cancer research, We here describe a simple and r eproducible method for the flow cytometric analysis of intracellular a ntigens such as cyclin-dependent kinase 2 (Cdk2) in rat aortic SMC. Th e sensitivity of the method was analyzed under growth and growth-inhib itory conditions using lovastatin, a cholesterol-lowering compound wit h antiproliferative capacity. Various antigens (Ras-protein, protein k inase C-alpha (PKC-alpha), Ki-67/MIB-1) in rat and bovine SMC were det ectable using this methodology which should have a wide range of appli cations.