are coated with anti cd4 antibodies so that cells expressing cd4 on their surface will bind to the beads after mixing of the cell suspension and the beads in the second chamber the resulting suspension is pumped into a third chamber through a size separation filter that allows particles smaller than 40 microns to pass and recycles larger clumps into the second chamber the third chamber then contains a population that is depleted for cells expressing cd4 if liquid containing a chemical or enzyme that breaks the binding between the beads and the anti cd4 antibodies is then added to the second chamber the bound cells can be re suspended and that suspension may be pumped into a fourth chamber which will then contain a population of cells enhanced for those expressing cd4 according to still another application a unitary particle processing cartridge 100 may be used to perform release testing of a product or substance for example a filter in the cartridge may trap a product or substance of interest such as bacteria in a sample that flows through the filter the trapped bacteria may then be collected from the filter for testing the unitary particle processing cartridge 100 may include a plurality of sample processing subsystems 110 in the cartridge for example two or more sample processing subsystems 110 may be disposed in series on the cartridge to allow sequential processing of a sample an enrichment region between the serial processing subsystems may allow for resetting of sample parameters between processes an example of a suitable enrichment region between two sample processing stages 110 is found in u s application ser no 10 329 008 the contents of which are herein incorporated by reference for example the enrichment region may be formed by a filter disposed between the.