PRECISE QUANTITATION OF ANTINUCLEAR ANTIBODIES ON HEP-2 CELLS WITHOUTTHE NEED FOR SERIAL DILUTION

Using HEp-2 cells as a substrate, we developed a method to quantitate antinuclear antibodies (ANA) by comparing the green fluorescence inten sity of unknown samples,vith that of calibrated standards, Intensity w as then converted to international units per milliliter by reference t o a standard curve, This method is accurate and precise around the cut off for positivity (5 to 10 IU/ml) and therefore provides a reliable s creening test for active, untreated systemic lupus erythematosus, Furt hermore, the method can identify sera likely to contain autoantibodies commonly detected in ANA-positive sera (SS-A, SS-B, Sm, small nuclear ribonucleoprotein, Scl-70, and double-stranded DNA).