Dear Editor, Autoimmune diseases are complex conditions where multiple aetiological factors, including genetics, epigenetics, environment, immunologic and hormonal, may converge. Several hormones are of interest in autoimmunity, such as oestrogens or progesterone, which have a described role in immune system function [1]. Clinical cases have shown association of primary hyperparathyroidism with development of monoclonal gammopathies or autoimmune diseases, with clinical and biological recovery after parathyroidectomy [2]. Previously, our group proposed that high levels of PTH could alter the normal function of B-lymphocytes and trigger the development of autoimmunity mediated by B-lymphocytes hyperactivity [3]. To evaluate the effects of PTH on B-lymphocytes, we determined the expression of PTH receptor (PTH1R) on B-lymphocytes from patients with SLE and primary Sjögren's syndrome (pSS), as well as healthy controls (HC). This staining was made by evaluating B-cell subsets and PTH1R expression from peripheral blood mononuclear cells by...