Background
Methods
Patients and control sera
RA1 (n = 373) | RA2 (n = 114) | |
---|---|---|
Female, n (%) | 254 (68.1) | 72 (63.2) |
RF IgM positivity, n (%) | 225 (60.3) | 109 (95.6) |
CCP2 IgG positivity, n (%) | 217 (58.2) | 114 (100) |
Anti-CarP IgG positivity, n (%) | 182 (49.2) | 114 (100) |
“Ever” smokers, n (%) | 160 (42.9) | 75 (65.8) |
Age (years), mean (SD) | 57.2 (15.8) | 54.5 (12.0) |
Measurement of anti-CarP antibody and ACPA isotypes and IgG subclasses
Statistical analysis
Results
The anti-CarP antibody response uses a wide spectrum of isotypes and IgG subclasses
Presence of anti-CarP antibody isotypes and IgG subclasses in ACPA-positive and ACPA-negative disease
The numbers of anti-CarP antibody isotypes and IgG subclasses are related to anti-CarP levels
Distribution of anti-CarP antibody and ACPA isotypes and IgG subclasses
Anti-CarP IgG1 antibodies are associated with more severe radiological damage, also in ACPA- and RF-negative RA
Broader IgG subclass usage associates with higher erythrocyte sedimentation rate and higher C-reactive protein levels
Number of isotypes | 0 (n = 135) | 1 (n = 120) | 2 (n = 77) | 3 (n = 40) | Ordinal OR (95% CI) |
p
| |
---|---|---|---|---|---|---|---|
Smoking (ever), n (%) | 54 (42.9) | 48 (43.6) | 35 (48.6) | 23 (60.5) | 1.38 (0.94-2.03) | 0.099 | |
SE positivity, n (%) | 79 (60.3) | 74 (63.2) | 57 (75.0) | 33 (86.8) |
1.91 (1.27-2.87)
|
0.002*
| |
ESR (mm/h), mean ± SD | 41.0 ± 25.6 | 40.2 ± 25.1 | 43.5 ± 27.7 | 47.8 ± 26.8 | 1.01 (1.00-1.01) | 0.206 | |
CRP (mg/L), mean ± SD | 29.0 ± 32.2 | 32.3 ± 36.4 | 29.9 ± 30.3 | 50.8 ± 47.0 |
1.01 (1.00-1.01)
|
0.017
‡
| |
Number of IgG subclasses | 0 (n = 150) | 1 (n = 104) | 2 (n = 57) | 3 (n = 44) | 4 (n = 18) | Ordinal OR (95% CI) |
p
|
Smoking (ever), n (%) | 58 (41.1) | 42 (42.4) | 30 (58.8) | 27 (65.9) | 3 (20.0) | 1.47 (1.00-2.16) | 0.051‡
|
SE positivity, n (%) | 89 (60.5) | 65 (64.4) | 46 (80.7) | 31 (75.6) | 13 (76.5) |
1.79 (1.19-2.69)
|
0.005*
|
ESR (mm/h), mean ± SD | 37.9 ± 23.2 | 37.7 ± 24.3 | 50.4 ± 31.1 | 52.3 ± 28.5 | 48.8 ± 21.6 |
1.01 (1.01-1.02)
|
<0.001*
|
CRP (mg/L), mean ± SD | 30.5 ± 32.9 | 28.1 ± 33.9 | 30.5 ± 34.8 | 45.4 ± 41.5 | 50.2 ± 42.9 |
1.01 (1.00-1.01)
|
0.020
|
Isotypes | IgG– (n = 190) | IgG + (n = 182) |
p
| IgA– (n = 221) | IgA + (n = 152) |
p
| IgM– (n = 312) | IgM + (n = 61) |
p
| |||
ESR, mm/h | 0.676 | 0.157 | 0.216 | |||||||||
Mean ± SD Median (IQR) | 41.2 ± 25.3 37.0 (33.3) | 42.9 ± 26.8 37.0 (44.5) | 40.4 ± 25.7 34.5 (33.0) | 44.2 ± 26.4 39.0 (43.0) | 41.2 ± 25.8 37.0 (35.0) | 45.7 ± 26.8 44.0 (45.0) | ||||||
CRP, mg/L | 0.694 |
0.039
| 0.092 | |||||||||
Mean ± SD Median (IQR) | 32.0 ± 35.7 19.0 (34.0) | 33.3 ± 35.4 19.5 (36.3) | 28.9 ± 33.3 17.0 (28.8) | 38.0 ± 38.0 23.0 (48.0) | 29.9 ± 31.8 18.0 (31.0) | 46.0 ± 48.3 23.5 (59.8) | ||||||
IgG subclasses | IgG1– (n = 33) | IgG1 + (n = 149) |
p
| IgG2– (n = 100) | IgG2 + (n = 82) |
p
| IgG3– (n = 157) | IgG3 + (n = 25) |
p
| IgG4– (n = 98) | IgG4 + (n = 84) |
p
|
ESR, mm/h | 0.176 | 0.156 | 0.323 |
<0.001*
| ||||||||
Mean ± SD Median (IQR) | 36.8 ± 24.2 32.0 (26.0) | 44.1 ± 27.3 37.0 (46.0) | 40.4 ± 26.3 34.0 (39.0) | 45.7 ± 27.4 44.5 (46.3) | 42.1 ± 26.9 34.5 (45.0) | 47.0 ± 26.6 51.0 (45.0) | 35.3 ± 23.2 30.0 (29.3) | 51.4 ± 28.3 49.0 (45.0) | ||||
CRP, mg/L | 0.637 |
0.023
| 0.107 |
0.003*
| ||||||||
Mean ± SD Median (IQR) | 27.5 ± 26.1 20.0 (30.0) | 34.7 ± 37.2 19.5 (39.3) | 29.0 ± 33.1 17.5 (31.8) | 38.7 ± 37.7 26.0 (41.0) | 31.1 ± 33.4 18.0 (33.5) | 47.5 ± 44.8 32.0 (58.5) | 25.3 ± 27.2 16.0 (28.0) | 42.1 ± 41.1 28.0 (52.0) |