1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) has been shown to modulate lymphocyte activation in vitro. Through binding to specific receptors 1,25-(OH)2 D3 inhibits proliferation, immunoglobulin production and the release of cytokines. Moreover, 1,25-(OH)2 D3 is efficiently produced by activated monocytes. These findings suggest that 1,25-(OH)2 D3 may play a role as a regulator of immunological activation. Consequently, we found it of interest to study the serum levels of the two major metabolites of vitamin D3 in patients with systemic lupus erythematosus (SLE) (n = 21), rheumatoid arthritis (RA) (n = 29) and osteoarthritis (n = 12). In patients with SLE the levels of 25-OH D3 were below those of the healthy controls (p = 0.0008) and OA (p = 0.0168). The levels 1,25-(OH)2 D3 corresponded to normal levels. There were no significant correlations between 25-OH D3 levels and clinical or paraclinical disease manifestations. Further, the phenotypic distribution of Gc-globulin, which binds vitamin D3 metabolites in circulation, was normal. The serum concentrations of 1,25-(OH)2 D3 and 25-OH D3 in patients with RA and OA corresponded to those of the controls. Although the cause of the reduced 25-OH D3 levels in SLE patients is unclear, possible beneficial effects of administration of vitamin D to these patients should be considered.

A new commercial method for measurement of anti-thyroid peroxidase (anti-TPO DYNOtest, Henning, Berlin) was evaluated in normal subjects and in patients with autoimmune thyroid and non-thyroid diseases, and compared to an immune fluorescence method for measurement of anti-microsomal antibodies (MicAb), and a radioimmunological method for quantifying thyroglobulin antibodies (TgAb). The majority of normal subjects had anti-TPO levels below 52 U/ml and patients with Hashimoto's thyroiditis had levels above 200 U/ml, with a good correlation to MicAb. In other autoimmune thyroid diseases the correlation was less pronounced. In non-thyroid autoimmune diseases MicAb showed falsely positive reactions in the presence of other autoantibodies, e.g. mitochondrial antibodies. The present study indicates that the anti-TPO method should probably replace measurements of MicAb for routine clinical use, thus providing a sensitive, precise, antigen specific method with the ability to reveal quantitative fluctuations. The study also indicates that TgAb could be abolished in routine diagnosis of autoimmune thyroid diseases and be reserved for special clinical situations, research purposes as well as measurement in sera before evaluation of serum thyroglobulin levels.

To evaluate longitudinal alterations in pulmonary function, 63 patients suffering from rheumatoid arthritis (RA) with previously reported reduced pulmonary diffusing capacity were re-examined in an 8-year follow-up study. Cross-sectional examination revealed normal values for vital capacity (VC), forced expiratory volume in 1 s (FEV1) and diffusing capacity per litre alveolar volume (KCO). Total diffusing capacity (DLCO; P < 0.0001), maximal expiratory flow at 75% of expired VC (MEF75; P < 0.0001) and MEF50 (P < 0.01) were decreased. Longitudinal evaluation revealed unchanged MEF50, MEF75 and FEV1, whereas increases in DLCO (P < 0.0001) and KCO (P < 0.0001) and a decrease in VC (P < 0.05) were found. The longitudinal changes in diffusing capacity were unrelated to patient age, disease duration, disease activity in the study period or pulmonary function at the first examination. Thus, in patients suffering from RA, the most prominent functional pulmonary abnormality, decreased diffusing capacity, appeared to improve in the course of time, despite a slight decrease in VC and continued articular disease activity.

Twenty-seven patients (25 women, 2 men) with primary Sjögren's syndrome, previously reported to have reduced pulmonary diffusing capacities were reexamined in a 7-year follow-up in order to evaluate longitudinal alterations in pulmonary function. Primary Sjögren's syndrome was diagnosed according to the Copenhagen criteria. The present examination revealed normal and unchanged values for vital capacity, forced expiratory volume in 1 s, maximal expiratory flow at 50% of expired vital capacity (MEF50), and diffusing capacity per liter alveolar volume. Total diffusing capacity (P less than 0.01) and MEF75 (P less than 0.05), were, however, significantly reduced compared with the predicted values, indicating pulmonary involvement primarily affecting the small airways. The longitudinal examination, furthermore, showed increasing values for total diffusing capacity (P less than 0.02), diffusing capacity per liter alveolar volume (P less than 0.001), and MEF75 (P less than 0.02), suggesting an improvement in lung status in the course of time. No correlation was found between MEF75 and diffusing capacities, nor between alterations in pulmonary function and complaints of dyspnoea, tiredness, cough, expectoration, tobacco smoking, or medical treatment with bromhexine, glucocorticosteroids, essential fatty acids, or nonsteroid antiinflammatory drugs.

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