Autoantibodies to C-reactive protein in incomplete lupus and systemic lupus erythematosus.

Abstract

OBJECTIVE: Anti-C-reactive protein (CRP) antibodies have been described in

patients with systemic lupus erythematosus (SLE). We investigated the potential

of the anti-CRP antibody as a marker for disease activity in SLE patients and as

a predictor of progression to SLE in patients with incomplete lupus. METHODS:

Immunoglobulin G anti-CRP antibody levels were measured using an enzyme-linked

immunosorbent assay. RESULTS: Patients with incomplete lupus exhibited clinical

and immunologic characteristics different from those in SLE patients: no

serositis and alopecia, more common oral ulcers and arthritis, lower disease

activity index, lower positivity for antinuclear and anti-double-strand DNA

antibodies, and higher complement levels. Anti-CRP antibody levels were higher in

SLE patients (35.6 [35.1] AU) than in patients with incomplete lupus (23.1 [25.8]

AU, P = 0.016) and normal controls (21.0 [14.3] AU, P < 0.001). Anti-CRP antibody

was significantly higher in SLE patients with arthritis and correlated with

disease activity markers, including antichromatin antibody. However, no

difference in anti-CRP antibody levels was observed between patients with

incomplete lupus that progressed to SLE and those whose did not. CONCLUSION:

These data suggest that anti-CRP antibodies can neither be used as biomarkers in

SLE nor predict SLE progression in patients with incomplete lupus.