Beneficial autoimmunity?

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.

Thyroid autoantibodies are associated with a reduced prevalence of frailty in community-dwelling older women

CONTEXT

The contribution of autoimmunity to the multisystem dysregulation that characterizes the frailty syndrome in older adults is unknown.

OBJECTIVE

The aim of the study was to investigate the relationship between thyroid antibodies and frailty in older women.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a cross-sectional study nested within the Women's Health and Aging Studies I and II. Thyroglobulin antibodies (TgAbs), thyroid peroxidase antibodies (TPOAbs), and antinuclear antibodies were measured in the baseline sera of 641 community-dwelling older women.

MAIN OUTCOME MEASURE

Frailty was defined using a validated five-component measure.

RESULTS

The prevalence of prefrailty and frailty was lower in TgAb-positive than negative older women (37.1 vs. 47.8% and 6.7 vs.11.9%, respectively; P = 0.01 and 0.03). The prevalence of prefrailty, but not frailty, was lower in TPOAb-positive than negative women (38.9 vs. 48.0% and 10.1 vs. 11.3%; P = 0.04 and 0.34). After adjustment for covariates including serum thyroid stimulation hormone concentration and thyroid medication usage in multinomial regression models, TgAb-positive older women had lower odds of prefrailty and frailty compared with TgAb-negative women (odds ratio 0.57 and 0.30; 95% confidence interval 0.34-0.98 and 0.10-0.85, respectively). Similarly, TPOAb-positive older women had lower odds of frailty compared with TPOAb-negative women (odds ratio 0.44; 95% confidence interval 0.20-0.96). These trends were not observed with antinuclear antibodies.

CONCLUSION

Independent of thyroid function status, community-dwelling older women who are seropositive for TgAbs and TPOAbs are less likely to be frail than seronegative women.

A Screening for the Occurrence of Autoreactive Antibodies in Sera of Pregnant and Non-pregnant Bitches

Sera of healthy pregnant (group I, n = 11) and non-pregnant (group II, n = 11) bitches were screened for autoantibodies (AAb). In both groups, blood samples were drawn every fifth day between days 5 and 55 after mating. Serum was analysed via indirect immunofluorescence (IIF) with the Canine ANA HEp-2 Screening Kit. In all animals, anticytoplasmic AAb were detected. Utilizing primate-heart substrate slides AAb against contractile proteins of the cytoplasm could be observed. The predominating fluorescence pattern in pregnant animals resembled above all desmin, which was proven via Western blot. The sera were then pre-incubated with tropomyosin, actin, vimentin, vinculin and keratin solutions, and assessed on HEp-2 slides and on human and canine fibroblasts as well. The latter substrate was used to verify whether the detected Ab were in fact AAb. Utilizing tropomyosin, revealed elimination of the cytoplasmic fluorescences on all three substrates. It is therefore assumed, that in sera of healthy dogs, AAb against contractile structure proteins of the cytoplasm are present regularly. The majority of pregnant bitches presented with higher end-point titres (EPT), than to be found in non-pregnant dogs. AAb against desmin played the key role in those patterns. In addition, sera were screened for thyroid specific AAb, namely thyroglobulin, thyroid peroxidase (TPO), T3 and T4, and for AAb against insulin by ELISA or Western blot (TPO). Only in two of the pregnant bitches a weak positive reaction (1:100) for T3-AAb was detected.

Relationship between naturally occurring human antibodies to casein and autologous antiidiotypic antibodies: implications for the network theory

Previous studies on human autologous antiidiotypes have been based largely upon analyses of autoimmune disease. We have previously described polyclonal, naturally occurring human autoantibodies directed against antibodies with specificity toward bovine casein in the sera of IgA-deficient humans. In order to define this system more exactly we have not produced two murine monoclonal antibodies directed against bovine milk kappa-casein to use as clonal tools to identify specific antiidiotypes in these human sera. Kappa-casein is an important part of the casein micelle in milk and cheese; in addition to being an important immunogen for man, kappa-casein is known to have conserved amino acid sequence and two antigenic epitopes. Data presented here show that the serum of up to 74% of IgA-deficient and 10% of normal humans have specific autologous antiidiotypes in their serum which bind to monoclonal antibodies directed to bovine kappa-casein. These human antibodies [intact or F(ab)'2] can be blocked from binding to the monoclonal anti-kappa-caseins by pure bovine kappa-casein or the kappa-casein peptide fragment. In contrast to previous studies in autoimmune disease, serum levels of the autoantiidiotypes were directly proportional to the level of IgG antibody to bovine kappa-casein. These observations suggest that continual exposure to a ubiquitous dietary antigen may produce an antigen driven system in which stimulation of both Ab1 and Ab2 occurs in concert.