Case report: An adverse response to cyclosporin A treatment in BALB/cJ mice.

Cyclosporin A (CsA) is an immunosuppressive drug that has been widely used in mice at a range of doses from 10 to 200 mg/kg. Our group carried out an experiment in 2016 where we delivered 75 mg/kg CsA (Neoral^TM) to BALB/cJ mice by oral gavage to enable wart formation in mice, which was moderately well-tolerated. We recently commenced another study using the same dose and route of delivery of CsA in BALB/cJ mice in order to immune suppress mice to make them susceptible for mouse papillomavirus infection. We highlight in this case report that in contrast to our earlier study, we observed almost immediate unexpected toxicity and had to terminate the recent experiment after only five days of treatment. Seven to eight-week-old female BALB/cJ mice were treated with 75 mg/kg of CsA by oral gavage daily for five days before treatment was stopped due to body weight loss and mice becoming moribund. The probability of survival of the mice following CsA treatment was 80% in this study, compared with 98% in our 2016 study. Mice showed signs of probable acute kidney injury, which was reversible following withdrawal of CsA. Although it is unclear why the clinical response to CsA in BALB/cJ mice differed markedly between the two experiments, this case report highlights the risk of CsA to mouse welfare. CD3 depletion has been used rather than CsA treatment in other studies and should be considered as an alternative to CsA treatment as it is immune-selective, and may be more effective at enabling wart formation in mice.