Abstract: The invention features methods of quantifying cells in a sample by lysing the cells followed by the measurement of at least one intracellular component. Methods of the invention are especially useful for quantifying small numbers of cells, e.g., over a large surface area or volume compared to the cell size. In a preferred embodiment, methods of the invention are performed using a microfluidic device.

Abstract: The invention features methods, devices, and kits for the isolation of analytes (e.g., a cell). A sample containing a desired analyte is introduced into a microfluidic device containing moieties that bind the desired analyte. A shear stress is applied that is great enough to prevent binding of undesired analytes and low enough to allow binding of the analyte of interest. Once bound, the desired analytes can be analyzed (e.g., counted). The invention also features methods for determining a shear stress for isolating a desired analyte.