• Open Access

Pharmacodynamic Monitoring of Canine T-Cell Cytokine Responses to Oral Cyclosporine


  • Study was performed at the Mississippi State University College of Veterinary Medicine.
  • Study was presented as an abstract at the 2010 ACVIM Forum in Anaheim, California (Abstract #122).

Corresponding author: Todd Archer, Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, P.O. Box 6100, Mississippi State, MS 39762; email: tarcher@cvm.msstate.edu.



Pharmacodynamic assays measure the immunosuppressive effects of cyclosporine on T-cells and offer an alternative assessment of efficacy in individual patients.


To assess the immunosuppressive effects of high and low dosage cyclosporine on canine T-cells and to develop a novel testing system for individualized dose adjustment.


Seven healthy female Walker hounds.


Experimental study using a paired comparison design. Flow cytometry was used to measure T-cell expression of IL-2, IL-4, and IFN-γ. Cytokine expression 8 days after oral administration of high and low dosages of cyclosporine was compared to baseline and washout values, respectively. The high dosage was initially 10 mg/kg q12h and was then adjusted to attain established immunosuppressive trough blood drug concentrations (>600 ng/mL). The low dosage was 5 mg/kg q24h.


High dosage cyclosporine resulted in significant decreases in IL-2 and IFN-γ expression (P = .0156, P = .0156), but not IL-4 expression (P = .2188). Low dosage cyclosporine was associated with a significant decrease in IFN-γ expression (P = .0156), while IL-2 expression was not affected (P = .1094).

Conclusions and Clinical Importance

T-cell function is suppressed at trough blood drug concentrations exceeding 600 ng/mL, and is at least partially suppressed in some dogs at low dosages. Direct evaluation of T-cell function could be an effective, more sensitive alternative to measuring blood drug concentrations for monitoring immunosuppressive therapy.