Figure 2

Distribution of Grp75 and calreticulin immunoreactivity in adult skeletal myofibers of myositis patients. Representative immunoreactivity for Grp75 in cryosections from biopsies of (a) a Group 0 subject (S7) and of myositis patients ((b) P5 from Group I, (c) P20 from Group II, and (d) P22 from Group III) after immunoperoxidase staining. (e) to (h) Distribution of Grp75 immunoreactivity with indirect immunoperoxidase in two additional Group I patients ((e) P7, and (g) P14) and that of type 1 fibers, identified by the immunoperoxidase staining for β-myosin heavy chain (βMy) of adjacent cryosections (f) and (h). (i) to (l) Comparison of the distribution of Grp75 immunoperoxidase labeling of two Group I patients, who differed for the degree of class I major histocompatibility complex antigen (MHC-I) immunoreactivity ((i) P9, grade ++ MHC-I; (k) P14, grade + MHC-I) with the presence of sarcolemmal immunofluorescence for MHC-I (j) and (l). Thin arrows in (k) and (l) indicate Grp75-positive and sarcolemmal MHC-I-positive fibers, whereas arrowheads indicate the presence of Grp75 immunoreactivity in sarcolemmal MHC-I-negative ones. (m) to (p) Representative histochemical demonstration for calreticulin immunoperoxidase in cryosections from biopsies of (m) a Group 0 subject (S1) and of myositis patients ((m) P6 from Group I, (o) P19 from Group II, and (p) P22 from Group III). Bar: 100 μm.