HTPS flow cytometry: A novel platform for automated high throughput drug discovery and characterization

The flow cytometer is unique among biomedical analysis instruments because it makes simultaneous and multiple optical measurements on individual cells or particles at high rates. High throughput flow cytometry represents a po tentially important multifactorial approach for screening large combinatori al libraries of compounds. Limiting this approach has been the availability of instrumentation acid methods in flow cytometry for automated sample han dling on the scale required for drug discovery applications. Here, we descr ibe an automated system in which a novel patented fluidics-based pharmacolo gy platform, the HTPS (High Throughput Pharmacological System), is coupled to a flow cytometer using a recently described plug flow-coupling valve tec hnology. Individual samples are aspirated sequentially from microplate well s and delivered to a flow cytometer for rapid multiparametric analysis. For primacy screening to detect and quantify cell fluorescence in endpoint ass ays, a high-speed no-wash protocol enabled processing of 9-10 cell samples/ min from 96-well microplates, In an alternate primary screening format, sol uble receptor ligands were sampled from microplate wells at rates of 3-4 sa mples/minute and successfully assessed for the ability to elicit intracellu lar calcium responses. Experiments with fluorescent beads validated the acc urate automated production by the HTPS of exponential and linear gradients of soluble compounds. This feature enabled rapid (2- to 3-min) characteriza tion of the intracellular calcium dose response of myeloid cells to formyl peptide as well as the quantitative relationship between formyl peptide rec eptor occupancy and cell response, HTPS flow cytometry thus represents a po werful high throughput multifactorial approach to increase the efficiency w ith which novel bioresponse-modifying drugs may be identified and character ized.