ANTIBODIES TO HIGH-MOBILITY GROUP PROTEINS IN SYSTEMIC-SCLEROSIS

Objective. To determine the prevalence of autoantibodies to high mobil ity group (HMG) proteins in systemic sclerosis (SSc). Methods. One hun dred ninety-seven unselected sera from patients diagnosed as SSc (n = 180) or Raynaud's phenomenon (RP) (n = 17) were tested for HMG autoant ibodies by ELISA and immunoblotting. Results. Seventy-one of the 180 ( 39.0%) SSc sera bound to HMG proteins in an ELISA: 56 (31%) to HMG-1 a nd/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 immun oblotting. Conclusion. 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 tr anscriptional complexes as targets of autoantibodies in scleroderma. T his is the first published report of HMG autoantibodies in scleroderma .