A survey of 42 hospitals revealed that the frequency of synovial fluid analysis was low (mean 3.9 per month). The mean was skewed upward by a higher frequency in 3 teaching hospitals, such that the overall median was 1.5 per month, with 15 hospitals studying 1 or less per month. There did not appear to be any consensus regarding what constitutes a routine synovial fluid analysis. Technical errors occurred, including dilution with acetic acid for cell counts and inappropriate use of automated cell counters. Twenty‐six laboratories studied 4 “unknown” fluids for crystals. In 50 opportunities to detect each crystal type, calcium pyrophosphate was detected only 6 times, and sodium urate was detected 39 times. The white blood cell count reported for a single fluid ranged from 2, 467–12,000/mm3 (mean ± SD 6,683 ± 1,992). The proportion of neutrophils identified varied from 0–30% (mean ± SD 13.8 ± 8.6). The majority of respondents believed that training and reference materials related to synovial fluid analysis should be improved.

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Modifications of the Farr ammonium sulfate precipitation assay for DNA antibodies have increased sensitivity and led to the detection of DNA binding in the sera of healthy subjects and subjects with rheumatic disease other than systemic lupus erythematosus (SLE). The presence of binding in immunochemically pure IgG and the pattern of inhibition by native and denatured DNA support the thesis that DNA binding of normal, non‐SLE, and SLE sera is antibody and similar in kind although not in degree. The presence of antibodies to DNA in normal and non‐SLE sera may limit the qualitative role of these antibodies in SLE and render DNA antibodies similar to antiglobulin and other antinuclear antibodies in rheumatic disease.

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