662 Incidence of Rejection after Conversion to Proliferation Signal Inhibitors after Heart Transplantation. Is There any Difference between CNI-Free vs CNI Minimization Regimens?

Purpose: To assess the effects of myxomavirus-derived immunomodulatory proteins (Serp-1 and M-T7), on circulating mononuclear blood cells (PBMC) isolated from cardiac transplant patients. Methods and Materials: PBMC were isolated from 21 orthotopic heart transplant patients, 16 without and 5 with documented allograft vasculopathy, ages18 66 years old; 1 to 204 months post heart transplantation; all receiving standard immunosuppression medications. Cell activation was assessed by adhesion assay with calcein cell labeling. Cell isolates were segregated into treatment groups: (1)saline for baseline control, (2)Dimethyl sulfoxide (DMSO) for vehicle control, (3)cell activation with phorbol myristate acetate (PMA), (4)Serp-1 with PMA and (5) M-T7 with PMA. The inhibitory effect of Serp-1 and M-T7 on cell activation was measured based on changes in the adherent cell counts quantified by a spectrofluorometer. Statistical analysis by ANOVA was then performed. Results: PMA treatment was unable to further activate cells from patients with diagnosed allograft vasculopathy suggesting chronic elevated activation in circulating PBMC resistant to further activationan. These cells did not respond to Serp-1 or M-T7 treatment. Cells from patients without allograft vasculopathy conversely were activated by PMA (p 0.0001). M-T7 suppressed cell activity in the patients without vasculopathy despite standard immunosuppressive regimen (p 0.0001), thus indicating that patients on full anti-rejection therapy display further responses to antiinflammatory therapy despite full therapeutic regimens. Conclusions: Patients with known cardiac allograft vasculopathy have ongoing chronic activation of circulating peripheral mononuclear cells, unresponsive to further activation or anti-inflammatory treatment. M-T7, a unique virus derived chemokine modulator, significantly suppressed cell activation in patients without vasculopathy, suggesting potential for further treatment despite current optimal medical immunosuppression.