Mature DC– and immature DC–derived exosomes display different quantitative protein compositions. (A,B) Proteins (10 μg) from DC lysate (DCs) or 3 μg of proteins from exosomes (Exo), either immature (i) or mature (m), were loaded on a 10% SDS gel followed by Western blotting using antibodies against proteins indicated on the right. (A) Proteins present in equal amounts in immature and mature exosomes. (B) Proteins up- or down-modulated on mature exosomes.