Expression of FcγRs in naïve knee joints of C57BL/6 and DBA/1 mice as detected by immunohistochemical staining using specific anti-FcγRII/III antibodies (mAb: 2.4G2) and subsequent development using di-aminobenzidine. (a) Naïve C57BL/6 mice. Very light staining of both synovial lining layer (arrows) and deeper layer. (b) Naïve DBA/1. Note the markedly higher staining intensity, especially of the cells of the synovial lining (arrows) (original magnification 200×).