Immunofluorescent detection of FXIII-A in primary monocyte-derived macrophages. Macrophages were treated for 6 days with IL-4 (20 ng/mL). After fixation and permeabilization, cells were probed with anti–FXIII-A antibody Ab-2 and with antibodies to Golgi markers GM130 (A) and TGN46 (B). (A-B top rows) The morphology represents the majority of cells present, and in these cells Ab-2 fluorescence was distributed throughout the cytosol. (A-B middle rows) Macrophages are shown that exhibited a morphology characteristic of migrating cells. In these cells, Ab-2 and Golgi marker fluorescence were colocalized in plasma membrane–associated ruffles and podosome-like structures. (A bottom row) A cell shows podosomes and membrane blebs containing both FXIII-A and GM130. In addition, candidate transport vesicles are present (arrowheads). The intracellular topology of these vesicles is established in supplemental Figure 3B. (B bottom row) A cell shows extensive colocalization of FXIIIA and TGN46 to the plasma membrane in addition to their presence in podosome-like structures. A representative TGN46-positive but FXIII-A–negative vesicle is shown with an arrowhead. TGN46-positive vesicles were apparent in most macrophages examined but were negative for FXIII-A in all fields examined.