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 cappin g protein gelsolin have defects in leukocyte and platelet function. Moreove r, dermal fibroblasts from gelsolin knockout (Gsn(-)) mice showed substanti ally reduced motility, membrane ruffling and pinocytosis. We have generated dendritic cells (DC) from spleens of Gsn- mice to investigate the importan ce 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 anti gen uptake and presentation can proceed in the absence of a major actin fil ament regulatory protein.