Autoantibodies against the calcium-sensing receptor and cytokines in autoimmune polyglandular syndromes types 2, 3, and 4

Summary

Objective

The frequency of autoimmunity against the parathyroid glands in patients with polyglandular autoimmunity that is not due to autoimmune polyendocrine syndrome type 1 (APS1) is unclear. To investigate this, the current study aimed to determine the prevalence of autoantibodies against parathyroid autoantigens the calcium-sensing receptor (CaSR) and NACHT leucine-rich-repeat protein 5 (NALP5) in a large group of patients with non-APS1 polyendocrine autoimmunity. Possible occult APS1 was investigated by cytokine autoantibody measurement and AIRE gene analysis.

Design, Subjects, and Measurements

Subjects were 178 patients with APS2, 3 or 4, and 80 healthy blood donors. Autoantibodies against the CaSR, NALP5, and cytokines were measured by immunoprecipitation, radioligand binding assays, or ELISA, respectively.

Results

Four patient samples (2.2%), but none of the controls, were positive for CaSR autoantibodies. NALP5 autoantibodies were not detected in any participant. Eleven patients (6.2%) had cytokine autoantibodies, but none of the control samples was positive. None of the patients with cytokine autoantibodies had any known or novel mutations in the AIRE gene.

Conclusions

The low prevalence of CaSR autoantibodies indicate a very low level of subclinical parathyroid autoimmunity in APS types 2, 3 and 4. In addition, autoantibodies against cytokines constitute an uncommon feature of non-APS1 polyglandular autoimmunity.

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