Multiplex immunoassay analysis of cytokines in idiopathic inflammatory myopathy.
BACKGROUND
Idiopathic inflammatory myopathies (IIMs), including dermatomyositis, polymyositis, and inclusion-body myositis, can be difficult to diagnose.


OBJECTIVE
To determine if a multiplex immunoassay for markers of inflammation in muscle homogenates correlates with a diagnosis of IIM.


METHODS
Frozen archived muscle biopsy specimens from 30 patients with IIM and 34 patients without IIM were homogenized and analyzed for cytokine content with a multiplex microbead-based immunoassay system. Analyte concentrations were normalized to total lysate protein concentration prior to comparison.


RESULTS
Two cytokines, interleukin 1ra and monocyte chemoattractant protein 1, and 1 soluble adhesion molecule, intracellular adhesion molecule 1, were found at significantly greater concentrations in muscle samples from patients with IIM. Intracellular adhesion molecule 1 levels alone were 83% sensitive and 91% specific for IIM at a cutoff of 1240 pg/mg muscle protein.


CONCLUSIONS
Immunoassays for selected inflammatory markers can serve in conjunction with histopathologic analysis as sensitive and specific tools for the diagnosis of IIM.
Baird
Geoffrey S
GS
Department of Pathology, University of Washington, Harborview Medical Center, Box 359645, Seattle, WA 98104-2499, USA. geoffsbaird@gmail.com
Montine
Thomas J
TJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018932:Chemokine CCL2 / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003882:Dermatomyositis / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007223:Infant; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D018979:Myositis, Inclusion Body / Q000175:diagnosis / Q000378:metabolism*; D017285:Polymyositis / Q000175:diagnosis / Q000378:metabolism*; D012680:Sensitivity and Specificity
D018932:Chemokine CCL2; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D018799:Intercellular Adhesion Molecule-1