Flow cytometry
Sputum samples were acquired on a BD LSRII flow cytometer (BD Biosciences) equipped with four lasers (405 nm, 488 nm, 561 nm, and 633 nm) or on a Navios EX (Beckman Coulter Life Sciences) equipped with three lasers (405 nm, 488 nm and 638 nm). The settings used on each flow cytometer had been previously shown to generate similar sputum profiles [