A method of conducting a quantitative analysis of a whole blood sample for viral or tumor load, wherein said whole blood sample comprises a plurality of cells including a cell surface marker for a virus or tumor, said method comprising a. adding said whole blood sample to a device comprising a tube defining a fluid flow channel comprising positioned therein a first set of segments forming a sample pre-treatment compartment and a second set of segments, said sample pre-treatment compartment comprising in one or more segments of said first set of segments a surface including immobilized anti-cell surface marker antibodies and wherein said sample pre-treatment compartment does not include a filter; b. mixing within the sample pre-treatment compartment said surface and sample in said device to form a depleted sample, wherein said depleted sample comprises < 5% cells including said cell surface marker and said mixing step is performed without a filter in the flow channel and under conditions that do not lyse cells in said sample; and c. measuring, in said device, the viral or tumor load in said depleted sample using a nucleic acid amplification technique, wherein said device further comprises a plurality of compression members operably connected with said first and second set of segments; wherein said first set of segments forming the sample pre-treatment compartment positioned within the fluid flow channel comprises, from a proximate to a distal end, a first flanking segment, an inner segment, and a second flanking segment, and said mixing step comprises selectively compressing one or more segments of said sample pre-treatment compartment by at least one compression member of said plurality of compression members to form a flow channel in the sample pre-treatment compartment such that the inner segment flow channel diameter is less than the diameter of the flow channel in the first and second flanking segments; and wherein said device comprises a second set of segments in said fluid flow channel defining a nucleic acid analysis region adjacent to said sample pre-treatment compartment, said nucleic acid analysis region comprising one or more additional segments each configured to conduct one or more steps of a nucleic acid analysis comprising reagent preparation, target enrichment, inhibitor removal, nucleic acid extraction, amplification and real-time detection. a. adding said whole blood sample to a device comprising a tube defining a fluid flow channel comprising positioned therein a first set of segments forming a sample pre-treatment compartment and a second set of segments, said sample pre-treatment compartment comprising in one or more segments of said first set of segments a surface including immobilized anti-cell surface marker antibodies and wherein said sample pre-treatment compartment does not include a filter; b. mixing within the sample pre-treatment compartment said surface and sample in said device to form a depleted sample, wherein said depleted sample comprises < 5% cells including said cell surface marker and said mixing step is performed without a filter in the flow channel and under conditions that do not lyse cells in said sample; and c. measuring, in said device, the viral or tumor load in said depleted sample using a nucleic acid amplification technique,