Reply to Wormser.

Abstract

To the Editor—Dr Wormser raises several important points about our study [1]. Although it is true that we did not measure doxycycline levels in our mice, we do wish to point out that each experiment with an immunodeficient mouse used wild-type mice of a matched genetic background. While it is possible the mutation in a gene that was responsible for the immunodeficiency could change doxycycline uptake from the gastrointestinal tract or protein binding, this has not been previously reported to our knowledge and would not be anticipated based on the known functions of these genes. Where we did compare across different genetic backgrounds of mice, we found no differences in the efficacy of doxycycline in the wild-type mice, suggesting that any differences are likely due to the specific mutation and not strain differences between the mice. Given the known importance of the immunodeficiencies we studied in immunologic...