Intravital Microscopy for Imaging and Live Cell Tracking of Alveolar Macrophages in Real Time

Classic in vitro coculture assays of pathogens with host cells have contributed significantly to our understanding of the intracellular lifestyle of several pathogens. Coculture assays with pathogens and eukaryotic cells can be analyzed through various techniques including plating for colony-forming units (CFU), confocal microscopy, and flow cytometry. However, findings from in vitro assays require validation in an in vivo model. Several physiological conditions can influence host-pathogen interactions, which cannot easily be mimicked in vitro. Intravital microscopy (IVM) is emerging as a powerful tool for studying host-pathogen interactions by enabling in vivo imaging of living organisms. As a result, IVM has significantly enhanced the understanding of infection mediated by diverse pathogens. The versatility of IVM has also allowed for the imaging of various organs as sites of local infection. This chapter specifically focuses on IVM conducted on the lung for elucidating pulmonary immune response, primarily involving alveolar macrophages, to pathogens. Additionally, in this chapter we outline the protocol for lung IVM that utilizes a thoracic suction window to stabilize the lung for acquiring stable images.