Antibodies to high mobility group proteins in systemic sclerosis.

To determine the prevalence of autoantibodies to high mobility group (HMG) proteins in systemic sclerosis (SSc). One hundred ninety-seven unselected sera from patients diagnosed as SSc (n = 180) or Raynaud's phenomenon (RP) (n = 17) were tested for HMG autoantibodies by ELISA and immunoblotting. Seventy-one of the 180 (39.0%) SSc sera bound to HMG proteins in an ELISA: 56 (31%) to HMG-1 and/or HMG-2; 29 (16%) to HMG-14/17. In the same assay, 7 of 17 RP sera (41%) bound to HMG proteins: 4 (23%) to HMG-1 and/or HMG-2, and 5 (29%) to HMG-14/17. The specificity of HMG binding was confirmed by immunoblotting. Antibodies to HMG proteins, particularly to HMG-1 and HMG-2 are found in about 1/3 of SSc Sera. Since HMG-1 and HMG-2 have a role in transcription, these observations further implicate transcriptional complexes as targets of autoantibodies in scleroderma. This is the first published report of HMG autoantibodies in scleroderma.