Session Time: 4:30pm-6:00pm
Presentation Time: 5:06pm-5:18pm
Location: Room 602/603/604
Although they represent a rapidly growing population, elderly organ transplant recipients are underrepresented in clinical trials. Age-specific aspects of established immunosuppressants are therefore poorly understood.
Here, we assessed the impact of immunosuppressive treatment with CTLA4-Ig, a fusion protein blocking costimulatory signaling between APCs and T cells through CD28, on alloimmune responses in old and young recipients (2-3 months vs. 16 months) in a fully MHC-mismatched murine transplantation models.
While treatment with CTLA4-Ig prolonged skin graft survival in young recipients, the same treatment was unable to prolong graft survival in old recipients. Conversely, cardiac allografts in young mice treated with CTLA4-Ig survived indefinitely, while 80% of old recipients treated with CTLA4-Ig had lost their graft after 100 days (log-rank test, p<0.001; n=5/group).
CTLA4-Ig reduced the in-vivo proliferation of CD4+ and CD8+ T cells (as assessed by BrdU incorporation) uniformly in both young and old recipients; in contrast, CTLA4-Ig reduced CD4+ central-memory and effector-memory T cells only in young but not old recipients. Moreover, systemic frequencies of CD4+IFN-γ+ T cells and systemic levels of IFN-γ cytokine production were reduced in young recipients, but remained unchanged in old. CTLA4-Ig caused significant perturbation in the Treg compartments with reduced frequencies and compromised proliferation of CD4+CD25+Foxp3+ cells. These differences correlated with a significant reduction in expression of CD28 on T cells in old mice, while levels of CTLA4 remained stable.
Immunosuppressive effects of costimulatory blockade with CTLA4-Ig showed distinct age-dependent effects in both skin and cardiac transplantation. Reduced expression of CD28 with aging may represent an escape mechanism for old alloreactive T cells, with unique clinical consequences for immunosuppression in the growing population of elderly transplant recipients.
CITATION INFORMATION: Heinbokel T., Quante M., Edtinger K., Minami K., Nian Y., Lau A., Elkhal A., Tullius S. Prolonged Graft Survival in Old Recipients is Abrogated by Immunosuppressive Treatment with CTLA4-Ig Am J Transplant. 2017;17 (suppl 3).
To cite this abstract in AMA style:Heinbokel T, Quante M, Edtinger K, Minami K, Nian Y, Lau A, Elkhal A, Tullius S. Prolonged Graft Survival in Old Recipients is Abrogated by Immunosuppressive Treatment with CTLA4-Ig [abstract]. https://atcmeetingabstracts.com/abstract/prolonged-graft-survival-in-old-recipients-is-abrogated-by-immunosuppressive-treatment-with-ctla4-ig/. Accessed July 7, 2020.
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