Secretion of pulmonary surfactant-like complexes by ATII-LCs.

<p>Confocal microscopy of DMSCs <i>(A)</i> and ATII-LCs <i>(B, C)</i> during stimulated exocytosis. Images are z-stack projections of multiple focal planes. Non-stimulated DMSCs and ATII-LCs were preincubated with LTG, showing green fluorescence originating from acidic compartments (e.g. lysosomes, late endosomes and Lamellar Bodies). Yellow fluorescence denotes FM 1–43 fluorescence, a lipid sensing probe. FM 1–43 was added to the cultures together with the secretagoges ATP and PMA immediately after time 0. Upon fusion of lipid-charged vesicles with the plasma membrane, bright yellow fluorescence resulted from FM 1–43 incorporation into secreted surfactant-like complexes. <i>(C)</i> Representative images of single confocal sections evidencing a high amount of secreted lipid assemblies associated to some ATII-LCs. Images were slightly corrected for a small loss in LTG fluorescence due to photobleaching. (Scale bar = 10 µm).