Autoantigens in an immunological network

Antinuclear Autoantibodies in Health: Autoimmunity Is Not a Synonym of Autoimmune Disease

The incidence of autoimmune diseases is increasing. Antinuclear antibody (ANA) testing is a critical tool for their diagnosis. However, ANA prevalence in healthy persons has increased over the last decades, especially among young people. ANA in health occurs in low concentrations, with a prevalence up to 50% in some populations, which demands a cutoff revision. This review deals with the origin and probable physiological or compensatory function of ANA in health, according to the concept of immunological clearance, theory of autoimmune regulation of cell functions, and the concept of functional autoantibodies. Considering ANA titers ≤1:320 as a serological marker of autoimmune diseases seems inappropriate. The role of anti-DFS70/LEDGFp75 autoantibodies is highlighted as a possible anti-risk biomarker for autoimmune rheumatic disorders. ANA prevalence in health is different in various regions due to several underlying causes discussed in the review, all influencing additive combinations according to the concept of the mosaic of autoimmunity. Not only are titers, but also HEp-2 IFA) staining patterns, such as AC-2, important. Accepting autoantibodies as a kind of bioregulator, not only the upper, but also the lower borders of their normal range should be determined; not only their excess, but also a lack of them or "autoimmunodeficiency" could be the reason for disorders.

Systemic lupus erythematosus: a role for anti-receptor antibodies?

Systemic lupus erythematosus (SLE) is considered by many to represent the best example of human disease where immune complexes play a primary role in the pathogenesis. SLE is thought to have an autoimmune basis; a conclusion based largely upon the propensity of these patients to form antibodies to cell nuclear components. The etiology of SLE remains unknown, as does the mechanism by which nuclear components are rendered autoantigenic. Here we present an argument for considering SLE as an antireceptor autoimmune disease, analogous to Graves' disease or myasthenia gravis. The proposed target of autoimmune attack, the estrogen receptor (ER), is normally resident in the nucleus, physiologically more active in women, and shed from hormonally responsive tissues during the course of the menstrual cycle. Autoantigenicity of ER is enhanced in SLE patients owing to a biochemical abnormality of estrogen metabolism which favors ligand occupancy of the receptor. The spectrum of anti-nuclear antibodies characteristic of SLE arises via normally functioning immune network regulatory mechanisms.