Catalytic antibodies in patients with systemic lupus erythematosus

Abstract

Objective: Antibodies with catalytic (hydrolytic) properties to DNA or RNA have been reported in sys-temic lupus erythematosus (SLE). However, it is well known that ethnicity plays an important role inthe presentation of SLE and severity of the disease; hence, these data may not truly represent a gen-eral feature of all SLE patients. Therefore, we have analyzed the hydrolyzing activity of immunoglob-ulin G (IgG) of SLE patients from the Indian population with an aim to decode whether the catalyticantibody response represents part of an active disease process.Methods: IgGs were isolated from the sera of 72 consecutive patients diagnosed with SLE. As a con-trol, IgGs from healthy donors were used. The catalytic activity of IgG was measured by PFR-MCA andaffinity-linked oligonucleotide nuclease assay.Results: IgGs from patients with SLE from the Indian subcontinent displayed significantly higherhydrolysis rates of both the surrogate substrate, PFR-MCA, and the DNA than IgG from healthy in-dividuals. Intergroup comparisons of the IgG-PFR-MCA interactions with clinical manifestations ofthe disease demonstrated a significantly increased level of hydrolysis among the patients with renalinvolvement who tested positive for anti-dsDNA antibodies. The PFR-MCA hydrolysis also appears tobe associated with the active disease (p=0.0988, vs. inactive group).Conclusion: The prevalence of catalytic antibodies represents a general feature of SLE patients, irre-spective of their origin.