Serum level of soluble CX3CL1/fractalkine is elevated in patients with polymyositis and dermatomyositis, which is correlated with disease activity

Table 1 Characteristics of the patients with polymyositis/dermatomyositis for serum analysis

	Healthy control serum (n= 20)	PM/DM patient serum (n= 29)
Number of PM/DM		7/22
Number of males/females	9/11	9/20
Age (years)	38.6 ± 2.1	55.3 ± 2.5
Duration of the disease (months)		21.6 ± 8.2
Number of cases of new onset/flare		23/6
Number of antinuclear antibody-positive		9 (n = 22)
Number of anti-Jo-1 antibody-positive		8 (n = 22)
Serum creatinine kinase (IU/l)^a		4,063.8 ± 1,466.9
Manual muscle testing score		39.0 ± 1.4 (n = 18)
Number of patients with ILD		19
AaDO₂ with ILD		31.5 ± 7.9 (n = 19)
Treatment at time of blood sampling
Untreated		19
Prednisolone alone		4
Prednisolone and cyclosporine		5
Prednisolone and methotrexate		1

Data presented as n or mean ± standard error of the mean. Antinuclear antibody was analyzed by immunofluorescence assay. The titer of anti-Jo-1 antibody was investigated by enzyme immunoassay. Although in some patients anti-dsDNA (n = 17), anti-RNP (n = 13), anti-Scl-70 (n = 4), and anti-SS-A (n = 12) antibodies and rheumatoid factor (n = 16) were analyzed, they were all negative. AaDO₂, alveolar-arterial oxygen pressure difference; ILD, interstitial lung disease; PM/DM, polymyositis/dermatomyositis. ^aNormal range: male < 197 IU/l, female < 180 IU/l.

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