Electron or confocal laser scan microscopy can be used for better characterization of morphological features or visualization of MPs. Indeed, here we show that sputum MPs display a range between 100 and 500 nm, larger than that previously shown for MPs obtained from edema fluid of a patient with ARDS [26] . However the most widely used method for studying MPs is flow cytometry due to its simplicity and the wealth of information that can be gleaned from the population under study [17] . The major advantage of flow cytometry is staining of MPs to determine the origin/cellular source of MPs. In addition, flow cytometry can also be used to enumerate blood MPs by adding a known number of fuorescent or non fuorescent latex particles to the sample prior to performing analysis [41] .