Humoral immunity and composition of immune complexes in patients with rheumatoid arthritis, with special reference to IgE-containing immune complexes.

IgE-containing circulating immune complexes (IgE-CIC) were determined with a 2.5% PEG-precipitation assay in 98 patients with classical or definite rheumatoid arthritis (RA). Of the 45 IgE-CIC positive sera, only 4 had elevated total serum IgE. IgE-CIC positive patients had more active disease than patients without IgE-CIC, as determined by their more swollen joints and higher Ritchie indices (p less than 0.04 and 0.02, respectively). Apart from IgE, other immunoglobulin isotypes, rheumatoid factor (RF) of the IgG-, IgA- and IgM-classes, C3 and antinuclear antibodies could be demonstrated in the IgE-containing PEG-precipitates. IgE-RF could not be demonstrated in serum or in IgE-CIC. Anti-IgE of the IgM-class (IgMaIgE) were frequently found (28/45 patients) in the IgE-positive PEG-precipitates. All 14 patients positive for IgGaIgE in the IgE-CIC were also positive for IgMaIgE in the CIC. As in the serum, there was a good correlation in the CIC between the level of IgGaIgE and the level of IgMaIgE (r = 0.64). The correlation between the respective levels of IgGaIgE and IgMaIgE in serum and in CIC was high (r = 0.93 and 0.79, respectively). On the other hand, only 1 patient was positive for IgAaIgE in the IgE-CIC. We conclude that IgE and aIgE of the IgM- and IgG-classes are frequently present in the immune complex form in RA and that they are correlated with the clinical activity of arthritis.

Pitfalls with anti-neutrophil cytoplasmic antibodies (ANCA).

A 39-year-old Ugandan student is described presenting with general malaise, fever and a pulmonary infiltrate. Open lung biopsy showing infarction and positive ANCA lead to a diagnosis of Wegener's granulomatosis and a treatment with immunosuppressive drugs was instituted. Five weeks after admission, however, sputum cultures turned out to be positive for Mycobacterium tuberculosis. The importance of ANCA-interpretation and the possibility of false positive results is discussed.

Use of the Saxon test as a measure of saliva production in a reference population of schoolchildren.

The Saxon test, a simple, reproducible, and low-cost technique to test for xerostomia in adults was applied to 347 schoolchildren who were free from any known disease. The values in children differed significantly from the values in adults and increased slightly with age. The test can easily be performed on samples kept for 8 days at 4 degrees C or at room temperature.