Suppressor cell function and anti-DNA antibody idiotypes in the serum of SLE patients and their first-degree relatives

Molecular mechanisms of autoimmunity

Autoimmune diseases result from a combination of genetic susceptibility factors and exogenous influences such as infection or chemical (including drug) exposure. Germline DNA variations in genetic type as well as defects in antigen recognition acquired during thymic education of developing T-lymphocytes both contribute to impaired self: nonself discrimination and set the stage for later development of such diseases as myasthenia gravis, polymyositis, or systemic lupus erythematosus. In addition, drugs such as D-penicillamine, hydralazine, procainamide, or quinidine induce T-cell or B-cell changes which precipitate auto-reactivity and cause drug-induced disease. Intervention in autoimmune diseases with prednisone, alkylating agents or the future use of more selective monoclonal antibody reagents may be life-saving in some of these disorders.

An analysis of autoimmunity through studies of DNA antibody idiotypes

The existence of idiotypic networks, first postulated over 12 years ago, is now widely recognised. Idiotypic analyses of autoantibodies have been reported among both hybridoma-derived and naturally occurring immunoglobulins. In this review the many studies of idiotypes detected on anti-DNA antibodies, notably one designated 16/6, are analysed to see what clues they offer to our understanding of autoimmunity. The links between infection and autoimmunity are emphasised by this analysis. It is also obvious that idiotypes first identified an autoantibodies are not confined to these immunoglobulins. Thus, the 16/6 idiotype originally described on a hybridoma-derived monoclonal anti-DNA antibody has also been identified on naturally occurring antibodies binding the Klebsiella polysaccharide K30.

Increased presence of common systemic lupus erythematosus (SLE) anti-DNA idiotypes (16/6 Id, 32/15 Id) is induced by procainamide

Sixty-seven patients on treatment with procainamide were examined for the presence of two common idiotypes of anti-DNA antibodies (16/6 Id and 32/15 Id). These idiotypes have been shown previously to have clinical relevance in patients with systemic lupus erythematosus (SLE). An enzyme-linked immunosorbent assay (ELISA) with rabbit anti-Id antibodies revealed increased concentrations of the 16/6 Id and 32/15 Id in 25 (37%) and 16 (24%) patients, respectively. Five of eight patients with drug-induced lupus had elevated titers of both idiotypes. A high correlation (R = 0.56, P less than 0.001 for 16/6 Id) was found between Id levels and anti-single-stranded DNA (ssDNA) antibody titers and between 16/6 Id titers and antihistone antibodies (IgG, R = 0.43; IgM, R = 0.25). It seems that procainamide, a component known to be associated with drug-induced lupus, may induce an increased production of common anti-DNA idiotypes in apparently normal subjects.