Significance of antibodies to cardiolipin in unselected patients with systemic lupus erythematosus: clinical and laboratory associations

Abstract

In a multicentre study anticardiolipin antibodies of the IgG and IgM isotypes were measured by a solid phase enzyme immunoassay in 368 patients with systemic lupus erythematosus (SLE) who were not selected on the basis of features of antiphospholipid syndrome. Clinical and laboratory associations of increased levels of anticardiolipin antibodies were evaluated. IgG and IgM antibodies to cardiolipin were documented in 224 (60.9%) and 128 (34.8%) patients, respectively. Regarding the symptoms of antiphospholipid syndrome, elevated amounts of anticardiolipin IgG were significantly associated with spontaneous abortion (P < 0.001), thrombocytopenia (P < 0.01), livedo reticularis (P < 0.01) and a positive direct Coombs test (P < 0.05), but not with thrombosis or central nervous system diseases such as epilepsy and psychosis. IgM antibodies to cardiolipin were associated with a positive direct Coombs test (P < 0.01), but with no other symptom of antiphospholipid syndrome. The predictive values of anticardiolipin antibody determinations in unselected SLE patients were poor for all features of antiphospholipid syndrome because of high proportions of false-positive and false-negative results. As for other manifestations of SLE, positive correlations between raised antibodies to double-stranded DNA and the occurrence of anticardiolipin antibodies of the IgG isotype were observed, and anticardiolipin IgM was negatively associated with nephritis.

IgM anti-dsDNA antibodies in systemic lupus erythematosus: negative association with nephritis

“…The data of this and other studies revealed that in addition to IgM anti-dsDNA antibodies, also IgM rheumatoid factors (manuscript in preparation), IgM anti-cardiolipin antibodies [9] and elevated serum IgM (data not shown) correlated negatively with nephritis. These parameters were not independent of each other: a pronounced positive association between IgM anti-dsDNA antibodies and elevated serum IgM or IgM anti-cardiolipin antibodies could be observed (Table 3).…”

“…Sera 352 SLE sera were obtained from aliquots of a stock frozen at -70°C that was previously collected in the German SLE study [9,10,11,12,13]. All 352 patients fulfilled at least four of the ACR criteria for the diagnosis of SLE [3,4].…”

“…In a previous study [9] we have shown that IgM anti-cardiolipin antibodies are negatively associated with lupus nephritis. In order to determine whether IgM parameters other than IgM anti-dsDNA antibodies may exert an independent negative influence on the development of lupus nephritis we performed a multivariate analysis including four IgM parameters (elevated serum IgM, IgM rheumatoid factor, IgM anti-cardiolipin antibodies and IgM anti-dsDNA antibodies).…”

“…In previous studies we have shown that the presence of IgM anti-cardiolipin antibodies is associated with a decreased prevalence of lupus nephritis [9]. Lupus nephritis, on the other hand, is associated with IgG anti-dsDNA antibodies which can be detected in the glomerula of the patients.…”

The prevalence, onset, and clinical significance of antiphospholipid antibodies prior to diagnosis of systemic lupus erythematosus

“…Antiphospholipid antibody (aPL) is another autoantibody that can occur in either the presence of or the absence of SLE, or even in healthy individuals. Antiphospholipid antibodies also occur in primary antiphospholipid syndrome (APS), viral infections (most notably human immunodeficiency virus), malignancy, and other autoimmune diseases (4)(5)(6).…”