Antibodies to hn-RNP protein A1 in systemic lupus erythematosus: Clinical association with Raynaud's phenomenon and esophageal dysmotility

Antibodies to recombinant hn-RNP protein A1 were found by ELISA in sera from 26 out of 67 unselected patients with systemic lupus erythematosus. A higher number of anti-A1 positive patients had Raynaud's phenomenon (50% vs 7%) and esophageal dysmotility (42% vs 5%) than the anti-A1 negative patients. All 8 patients with both Raynaud's phenomenon and esophageal dysmotility had a positive anti-A1 assay. No association was found with other clinical findings, nor with disease activity and treatment regimes. Anti-A1 antibodies did not correlate with anti-RNP and anti-Sm antibodies, which were present in 30% and 12% of the anti-A1 positive cases and in 22% and 7% of the anti-A1 negative cases, respectively. Our results indicate that antibodies to hn-RNP protein A1 may be associated with a subset of SLE patients with clinical features overlapping those of progressive systemic sclerosis and quite distinct from the group identified by anti-RNP antibodies.