Detection of antilymphocyte antibodies in patients with systemic lupus erythematosus by indirect immunofluorescence on acetone-fixed lymphocytes.

Antilymphocyte antibodies in normal and SLE sera were found to react with lymphocytes fixed in acetone at -30 degrees C. for 10 minutes. At a dilution of 1:40, 3.7 per cent of normal and 90.9 per cent of SLE sera were positive with the use of indirect immunofluorescence with a pepsin-digested, FITC-labeled anti-Fab serum. The reaction was independent of temperature between 4 degrees and 37 degrees C. Three patterns of staining were seen in the lymphocyte surface: reticular, ring, and globular. The ring pattern appeared to correlate with IgM, and the reticular and globular patterns with IgG antilymphocyte antibodies. Absorption with lymphocytes, insolubilized extracts of rat liver and kidney, and human brain revealed that antilymphocyte and ANA activity could be independently removed. Variation in reactivity with cells from different normal donors was similar to that seen with the microcytotoxicity test. Acetone-fixed lymphocytes appear to be a much more sensitive target than viable cells in suspencion in IIF tests for antilymphocyte antibodies. The IIF test with fixed cells also appears slightly more sensitive than cytotoxicity testing and has the advantage of allowing storage of target cells.