Autoantibodies recognizing the 27 carboxy-terminal amino acids of calpastatin are associated with secondary Sjögren syndrome in systemic lupus erythematosus.

The objective of this study was to determine in systemic lupus erythematosus (SLE) the prevalence and clinical significance of anticalpastatin antibodies (ACAST), an autoantibody population previously detected in sera from patients with various connective tissue diseases. Eighty-four patients with SLE (mean age: 30 years at diagnosis, females 77) that fulfilled ACR criteria were included in the study retrospectively. Several clinical and biological data were collected. ACAST were detected by a solid-phase enzyme linked immunosorbent assay (ELISA) using as antigen a synthetic peptide corresponding to the 27 C-terminal amino acids of calpastatin (CAST-C27). The prevalence of ACAST-C27 was 13% (11/84) in SLE patients. No correlation was found between the presence of ACAST-C27 and clinical manifestations such as thrombosis and vasculitis. Furthermore, no correlation was observed with the presence ofantiphospholipid antibodies (APL). However, we found a statistically significant association between the presence of ACAST-C27 and that of secondary Sjögren syndrome (P = 0.01). The conclusion is ACAST-C27 are not associated with thrombosis in SLE patients. The association observed between ACAST-C27 and secondary Sjögren syndrome suggests that ACAST-C27 might be useful in discriminating a clinical subgroup of SLE patients.