Table 1

Relative concentration of specific ACPA, anti-CCP2 and circulating immune complexes (CIC) in sera and synovial fluids

SequenceNumber of patients reacting in serum (%)Serum median (mean)SF median (mean)P values
(Wilcoxon)
Compartment with highest levelSerum/
IgG median (mean)
SF/
IgG median (mean)
P values
(Wilcoxon)
Compartment with highest level
Filaggrin 307–324 (CCP1)HQCHQEST(cit)GRSRGRCGRGS (cyclic)55/77 (71)38.89 (233.82)17.07 (185.86) 0.0005 Serum3.16 (22.69)4.19 (36.59) 0.0282 SF
Vimentin 2–17ST(cit)SVSSSSY(cit)(cit)MFGG40/77 (52)2.7 (14.78)−0.43 (19.40)0.91790.14 (1.27)−0.11 (3.79)0.561
Vimentin 60–75VYAT(cit)SSAV(cit)L(cit)SSVP48/77 (62)36.76 (195.93)11.5 (168.09)0.05752.63 (18.14)4.00 (36.36) 0.0009 SF
Fibrinogen α36–50GP(cit)VVE(cit)HQSACKDS22/77 (29)0 (61.38)0 (53.56)0.18220 (4.67)0 (9.67) 0.0355 SF
Fibrinogen α563–583HHPGIAEFPS(cit)GKSSSYSKQF47/77 (61)10.05 (107.30)6.48 (82.61) 0.0378 Serum1.02 (10.51)1.08 (18.02) 0.0216 SF
Fibrinogen α580–600SKQFTSSTSYN(cit)GDSTFESKS25/77 (32)0 (43.90)0 (27.70)0.13980 (4.65)0 (7.61)0.5338
Fibrinogen α621–635(cit)GHAKS(cit)PV(cit)GIHTS36/77 (47)0 (121.15)0 (91.35)0.37560 (13.33)0 (20.48)0.0987
Fibrinogen β36–52NEEGFFSA(cit)GHRPLDKK47/77 (61)14.38 (156.83)7.44 (132.73) 0.039 Serum1.33 (13.84)2.32 (27.04) 0.0087 SF
Fibrinogen β60–74(cit)PAPPPISGGGY(cit)A(cit)52/77 (68)17.7 (170.93)7.49 (156.08) 0.0292 Serum1.46 (14.62)2.40 (30.47) 0.0005 SF
Fibrinogen β62-81(Fib72)APPPISGGGY(cit)ARPAKAAAT25/77 (32)0 (11.19)0 (7.09)0.93110 (1.16)0 (1.60)0.936
Fibrinogen β62-81(Fib74)APPPISGGGYRA(cit)PAKAAAT22/77 (29)0.55 (35.02)0.73 (32.12)0.26920.06 (2.76)0.11 (6.08) 0.0305 SF
α-Enolase 5-21(CEP-1)CKIHA(cit)EIFDS(cit)GNPTVEC (cyclic)49/77 (64)72.82 (263.44)32.4 (235.90) 0.0183 Serum7.85 (22.65)6.79 (55.09) <0.0001 SF
hnRNP 1(proprietary)*28/77 (36)9.79 (70.52)6.44 (53.49) 0.0003 Serum0.89 (6.06)1.72 (10.64) <0.0001 SF
hnRNP 5(proprietary)*49/77 (64)19.8 (134.97)9.14 (120.27)0.11911.67 (12.52)2.36 (26.61) 0.0005 SF
hnRNP Z1(proprietary)*35/77 (45)0 (65.53)0.83 (56.09)0.44640 (6.47)0.25 (13.54) 0.0283 SF
hnRNP Z2(proprietary)*46/77 (60)4.96 (128.27)6.21 (105.07)0.17260.43 (13.44)2.75 (24.81) 0.0066 SF
hnRNP Bla26(proprietary)*41/77 (53)4.57 (45.95)0.81 (45.32)0.24910.43 (4.13)0.46 (8.74) 0.005 SF
Histone4 14–34GAK(cit)H(cit)KVL(cit)DNIQGITKPAI32/77 (42)18.77 (109.76)11.64 (81.80) <0.0001 Serum1.66 (9.79)2.14 (15.51) 0.0053 SF
Histone4 31–50KPAI(cit)(cit)LA(cit)(cit)GGVK(cit)ISGLI47/77 (61)11.04 (101.92)4.79 (67.97) 0.029 Serum0.75 (10.42)1.36 (11.51)0.3402
Anti-CCP255/77 (71)132 (317.25)55 (153.99) <0.0001 Serum11.60 (29.44)10.48 (39.95) 0.0053 SF
CIC µg Eq/mL0.53 (12.35)0.27 (5.87) 0.0252 Serum0.042 (1.112)0.054 (0.914)0.5018
  • Values are shown both as arbitrary units in sera and SF, as well as after correction for total IgG levels in the corresponding serum or SF samples. Comparisons were performed with the Mann-Whitney U test; significant differences are depicted in bold. The second column details the sequences of the citrullinated peptides in the multiplex assay, using the single-letter amino acid code and ‘(cit)’ for citrulline. The not listed arginine-containing control peptides have identical sequences except that they contain arginine residues instead of citrulline.

  • *Peptides are derived from hnRNP A3. Available on request from KS; see authors’ details.

  • ACPA, anti-citrullinated protein/peptide antibodies; SF, synovial fluid.