C1-inhibitor autoantibodies in SLE

Abstract

The presence of anti-C1-inhibitor (anti-C1-INH) autoantibodies is a hallmark of acquired C1-inhibitor deficiency. However, only scarce data are available on their prevalence, diagnostic value, and/or significance in systemic lupus erythematosus (SLE). In a multicentre study, we determined the levels of autoantibodies to C1-inhibitor in sera from 202 patients with SLE and 134 healthy controls. Additional clinical and laboratory parameters, such as organ involvement, as well as anti-C1q, anti-double-stranded DNA antibody, erythrocyte sedimentation rate, C-reactive protein, C3 and C4 serum complement levels have been studied in patients. The level of anti-C1-INH IgG was significantly higher (p = 0.034) in SLE patients, than in the controls. A high anti-C1-INH level of > or =0.4 U/ml (mean of controls + 2 SD) was found in 17% of the patients, but in only 4% of the controls (p = 0.0003). The SLEDAI score was significantly higher (p = 0.048) and the duration of SLE was significantly longer (p = 0.0004) among patients with elevated anti-C1-INH levels compared with patients without this autoantibody (median disease duration 8 vs. 17 years, respectively). Anti-C1-INH level was not correlated with any other laboratory parameter or organ manifestation of the disease. These findings indicate that the anti-C1-INH level is higher in SLE patients than in healthy controls and furthermore, the anti-C1-INH level correlates with the duration and activity of the disease.

Complement C1 Esterase Inhibitor Levels Linked to Infections and Contaminated Heparin-Associated Adverse Events

“…Although the genetic deficiency of C1inh in humans, hereditary angioedema, is a very rare life-threatening disorder [11], [23], [37], [38], there may be some asymptomatic patients who are missed, including relatives of known cases [39]. Consumption of C1inh may occur in patients with autoimmunity such as SLE [40], [41], [42], [43]. Antibodies to C1 inh have been observed in some healthy individuals as well as SLE patients [43] and such antibodies may predispose healthy individuals to contact system stressors such as OSCS.…”

“…Consumption of C1inh may occur in patients with autoimmunity such as SLE [40], [41], [42], [43]. Antibodies to C1 inh have been observed in some healthy individuals as well as SLE patients [43] and such antibodies may predispose healthy individuals to contact system stressors such as OSCS. Adaptive C1inh deficiency can be observed in patients with B cell lymphoma [21], [44].…”

Phenocopies: Mimics of Inborn Errors of Immunity

“…This kind of autoantibodies has been found in patients with Systemic Lupus Erythematosus (SLE) although not related to manifestations other than those of the disease. The presence of this autoantibodies is related with the duration of disease activity [91]. Table 4 shows the useful clinical data for an adequate differential diagnosis in patients with angioedema and in whom this phenocopy is suspected [92].…”

Laboratory tests for disorders of complement and complement regulatory proteins

“…Conversely, in HAE, C1q is normal. AAE is seen in patients with chronic lymphoproliferative disorders such as multiple myeloma as well as in select cases of SLE, which have rarely been described to have autoantibodies to C1 inhibitor .…”