Table 2

Performance of the 12 investigated citrullinated peptides

Peptide

Percentage of RA sera reacting with the individual citrullinated peptidesa (%) at 98.0% specificity

Number of positive patients/number of CCP2-positive patients (%)a

Percentage of RA sera reacting with the individual citrullinated peptides (%) at 98.0% specificity after arginine subtractionb

Number of positive patients/number of CCP2-positive patients (%)b after arginine subtraction

Positive (+) or negative (-) effect of arginine subtraction on the diagnostic performance


Eno5-21 (CEP-1)

39.4

91.0

40.9

94.5

+


Vim60-75

31.9

73.7

40.0

92.4

+


Vim2-17

10.8

24.9

8.0

18.5

-


Fil307-324 (CCP1)

32.8

75.8

32.5

75.1

-


Fibβ36-52

45.2

104.4

41.9

96.8

-


Fibβ563-583

31.0

71.6

31.5

72.7

+


Fibβ580-600

10.5

24.2

9.8

22.6

-


Fibβ62-81a

19.8

45.7

20.6

47.6

+


Fibβ62-81b

28.0

64.7

26.1

60.3

-


Fibβ60-74

38.8

89.6

37.3

86.1

-


Fibα621-635

25.9

59.8

29.0

67.0

+


CII 359-369 (CitC1)

18.8

43.4

NDc

NDc

NDc


Peptides names are designated as in Table 1.

aThese percentages should be compared with the fact that 43.3% of all RA patients in the present selection of EIRA patients were anti-CCP2 positive.

bFluorescence intensities for the arginine control peptides were subtracted from the fluorescence intensities for each measurement among RA patients and controls, whereupon the performance was calculated on the net values.

cNo subtraction was done for this peptide as the arginine control peptide is itself an autoantigen with conformational epitopes that are destroyed by citrullination [20].

Hansson et al. Arthritis Research & Therapy 2012 14:R201   doi:10.1186/ar4039

Open Data