Open AccessMajor Histocompatibility Complex I and II Expression and Lymphocytic Subtypes in Muscle of Horses with Immune‐Mediated Myositis
Author(s) -
DurwardAkhurst S.A.,
Finno C.J.,
Barnes N.,
Shivers J.,
Guo L.T.,
Shelton G.D.,
Valberg S.J.
Publication year - 2016
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.14371
Subject(s) - dysferlin , myopathy , major histocompatibility complex , medicine , cd8 , pathology , immunology , dystrophin , immune system , sarcolemma , biology , muscular dystrophy , skeletal muscle
Background Major histocompatibility complex ( MHC ) I and II expression is not normally detected on sarcolemma, but is detected with lymphocytic infiltrates in immune‐mediated myositis ( IMM ) of humans and dogs and in dysferlin‐deficient muscular dystrophy. Hypothesis/Objectives To determine if sarcolemmal MHC is expressed in active IMM in horses, if MHC expression is associated with lymphocytic subtype, and if dysferlin is expressed in IMM . Animals Twenty‐one IMM horses of Quarter Horse‐related breeds, 3 healthy and 6 disease controls (3 pasture myopathy, 3 amylase‐resistant polysaccharide storage myopathy [ PSSM ]). Methods Immunohistochemical staining for MHC I, II , and CD 4+, CD 8+, CD 20+ lymphocytes was performed on archived muscle of IMM and control horses. Scores were given for MHC I, II , and lymphocytic subtypes. Immunofluorescent staining for dysferlin, dystrophin, and a‐sarcoglycan was performed. Results Sarcolemmal MHC I and II expression was detected in 17/21 and 15/21 of IMM horses, respectively, and in specific fibers of PSSM horses, but not healthy or pasture myopathy controls. The CD 4+, CD 8+, and CD 20+ cells were present in 20/21 IMM muscles with CD 4+ predominance in 10/21 and CD 8+ predominance in 6/21 of IMM horses. Dysferlin, dystrophin, and a‐sarcoglycan staining were similar in IMM and control muscles. Conclusions and clinical importance Deficiencies of dysferlin, dystrophin, and a‐sarcoglycan are not associated with IMM . Sarcolemmal MHC I and II expression in a proportion of myofibers of IMM horses in conjunction with lymphocytic infiltration supports an immune‐mediated etiology for IMM . The MHC expression also occured in specific myofibers in PSSM horses in the absence of lymphocytic infiltrates.