Autoantibodies to poly(ADP-ribose)polymerase in centenarians: a reappraisal of Grabar's hypothesis.

BACKGROUND: Centenarians display a characteristic autoantibody profile, this being the absence of organ-specific autoantibodies and an increase in non-organ-specific autoantibodies without any full-blown autoimmune disease. OBJECTIVE: Antibodies directed to the nuclear protein poly(ADP-ribose) polymerase (PARP) were frequently found in the sera of patients affected by autoimmune diseases. This study aims at investigating the presence of circulating autoantibodies directed against PARP-1 in normal subjects, and searching for a possible correlation between level of circulating autoantibodies and age. METHODS: The presence of antibodies to PARP was monitored by ELISA according to a previously developed protocol. Data were analysed by parametric statistics (unpaired t test, chi(2) test). RESULTS: Our study performed on 33 centenarians and 66 subjects of age ranging from 12 to 80 years shows that circulating autoantibodies to the nuclear enzyme PARP, previously described in autoimmune diseases, are present in the sera of normal healthy people and increase with age. CONCLUSIONS: Taking into account the role of PARP-1 in DNA damage and apoptosis, the data are compatible with Grabar's hypothesis, which proposed several decades ago that 'autoreactive antibodies represent a physiological system for disposing the products of metabolism and catabolism', thereby helping to attain longevity.