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C5b-9 deposits on endomysial capillaries in non-dermatomyositis cases

Anne K Braczynski1, Patrick N Harter1, Pia S Zeiner1

  • 1Edinger Institute, Institute of Neurology, University of Frankfurt am Main, Germany.

Neuromuscular Disorders : NMD
|March 30, 2016
PubMed

Insights

Deposits of the membrane attack complex (MAC) C5b-9 in endomysial capillaries are not exclusive to dermatomyositis (DM). Distribution patterns differ between DM and non-DM cases, necessitating critical assessment.

Area of Science:

  • Immunology
  • Neurology
  • Pathology

Background:

  • Terminal-membrane-attack-complex (MAC) C5b-9 deposits on endomysial capillaries are a hallmark of dermatomyositis (DM).
  • The precise role and diagnostic specificity of these deposits remain under investigation.
  • C5b-9 deposition is linked to microinfarctions and vascular damage in muscle tissue.

Purpose of the Study:

  • To investigate the presence and distribution patterns of C5b-9 deposits in endomysial capillaries in patients without DM.
  • To differentiate capillary C5b-9 accumulation patterns between DM and non-DM cases.
  • To assess the relationship between C5b-9 deposits, capillary density, and myofiber necrosis.

Main Methods:

  • Immunohistochemistry was used to evaluate endomysial capillary C5b-9 deposits.
  • Analysis included 19 patients with C5b-9 accumulation (12 DM, 8 non-DM controls).
  • Quantification of C5b-9 positive myofibers, capillary density, and myofiber necrosis was performed.

Main Results:

  • Similar numbers of C5b-9-positive myofibers were observed in both DM and non-DM cases.
  • DM cases showed significantly more perifascicular capillary C5b-9 deposits compared to non-DM cases.
  • Non-DM cases exhibited a more diffuse pattern of endomysial capillary C5b-9 deposits.
  • DM patients had significantly more C5b-9-positive necrotic fibers than non-DM patients, despite similar total capillary density.

Conclusions:

  • Endomysial capillary C5b-9 deposits are found in various non-DM conditions.
  • The distribution pattern of C5b-9 deposits is crucial for differentiating DM from other myopathies.
  • Capillary C5b-9 deposition requires critical assessment considering its varied distribution patterns.
Keywords:
C5b-9DermatomyositisMHC-IMicrovascular unitMuscle disease

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