Response to: ‘Lack of standardization of ANA and implications for drug development and precision medicine’ by Mahler

We appreciate Dr Mahler’s1 comments on our paper, ‘Assay variation in the detection of antinuclear antibodies in the sera of patients with established SLE’,2 by Pisetsky and colleagues, and the thoughtful discussion on the technical issues that affect the testing for antinuclear antibodies (ANA) by immunofluorescence assays with HEp-2 cells (IFA). We agree that our sample size was relatively small and that we did not present confidence limits on the frequency of positive responses. Rather than attempting to revalidate the assays, we …