Aspects of the present disclosure include methods for processing a biological sample. Methods according to certain embodiments include contacting a biological sample having cells with an assay reagent that includes one or more analyte-specific binding members to produce a biological sample assay composition and introducing the biological assay composition into an inlet of a flow cytometer having an integrated acoustic separator. Systems, including a flow cytometer with integrated acoustic separator having one or more acoustic concentrator devices suitable for practicing the subject methods are also described.