Modern and effective biomedical research needs new and effective methods. Use of 96-well micro-titre plates allows the performance of many experiments and samples under the same conditions. The methods used to determine cell numbers in these plates are all end-point methods. These methods allow only one determination per plate, and the cells are lost. Usually, such assays are performed according to concentration dependance. Other parameters and cell growth dynamics remained unrevealed. To reveal cell growth dynamics, multiple assays should be performed. Such an experimental approach would be expensive and time-consuming, so it is rarely performed. To fill this gap, the Institut fu/spl uml/r Angewandte Mikrobiologie (IAM) and SLT Labinstruments developed GCSS (General Cell Screening System). GCSS is a powerful hardware/software system that enables continuous monitoring of cell growth without any treatment or stain. The method is based on a high-resolution turbidity measurement performed directly on the cell culture plate. The system consists of a reader and an eight-channel photometer, a plate with a new form of wells, an Apple Macintosh computer and the GCSS software. We chose a classic bone-marrow colony-count assay, which is a typical assay scored after seven days of incubation and based on one measurement only. GCSS allowed us to seed bone marrow cells in microtitre plates in a medium with different concentrations of haemopoietic growth factors and to perform multiple measurements. We observed bone-marrow cell growth derived from interferon alpha-treated mice and compare the cell growth from placebo-treated mice. The classical bone marrow assay only allowed scientists to confirm the suppressive nature of interferon alpha on bone marrow cells in-vivo. Multiple measurements with GCSS allowed us to collect cell growth data over seven days of incubation which could not be seen in the colony-count assay. The data collected with GCSS could not confirm the suppressive n...