Membrane ruffling, macropinocytosis and antigen presentation in the absence of gelsolin in murine dendritic cells

Previous studies have shown that mice lacking the actin-severing and capping protein gelsolin have defects in leukocyte and platelet function. Moreover, dermal fibroblasts from gelsolin knockout (Gsn^-) mice showed substantially reduced motility, membrane ruffling and pinocytosis. We have generated dendritic cells (DC) from spleens of Gsn^- mice to investigate the importance of gelsolin in antigen endocytosis and processing. We show here that Gsn DC produce apparently normal membrane ruffles which can resolve to form large macropinosomes. Moreover, presentation of exogenous antigens on both MHC class II and class I molecules was equivalent in Gsn^- and wild-type DC. Thus the major rearrangements of the actin cytoskeleton needed for DC antigen uptake and presentation can proceed in the absence of a major actin filament regulatory protein.