Introduction: Older renal transplant recipients have a lower risk of rejection, but are at increased risk for infectious complications. An immune risk profile (IRP) has been proposed which is associated with mortality in the elderly and increased infectious complications post-transplant. We conducted a cross sectional study of elderly renal transplant candidates to determine incidence of IRP, its association with the ImmuKnow® assay, T and NK cell phenotypes, and define clinical factors that contribute to this IRP.

Methods: We recruited 59 subjects into 5 cohorts including healthy controls, CKD patients <65 yo, CKD ≥65 yo, Dialysis <65 yo and dialysis ≥65 yo. T and NK cell phenotypes were assessed by multicolor flow cytometry, CMV serostatus determined and T cell function evaluated using the ImmuKnow® assay. Multivariable linear regression was performed to evaluate the relative contributions of age, CKD and dialysis status compared to controls and IRP+ and CMV+/IRP- compared to CMV- patients.

Results: There were no differences in the clinical characteristics between the study groups except for their age. The IRP, defined as CMV seropositivity and CD4/CD8 ratio < 1 or being in the highest quintile of CD8+ senescent (CD28-/CD57+) T cells, identified 13 IRP+ individuals who were equally divided amongst the 5 cohorts. CMV seropositivity was the only risk factor for IRP. IRP+ subjects showed significant elevations of total CD8+ and CD8+ TEMRA cells. There was a marked decline in naïve CD4+ and CD8+ cells as well as decreased total CD4+ cells. Senescent cells were seen almost exclusively in IRP+ patients. IRP+ was associated with decreased proportions of CD27+ and KLRG1+ NK cells. ImmuKnow value was negatively correlated to age and was lower in IRP+ patients. CMV+/IRP- patients were similar to CMV- patients. CKD and dialysis status was not associated with T cell phenotype, but was associated with increases in FcgR[Delta]g and NKG2C+ NK cells.

Conclusion: Age and dialysis status do not predict immune senescence in kidney transplant candidates. While the ImmuKnow assay is lower in IRP+ patients, its variability does not permit its use to predict the IRP. A complete IRP should include an expanded T and NK cell phenotyping and further studies are required to evaluate conclusively whether pre-transplant immune phenotype can allow personalization of immune suppression.

CITATION INFORMATION: DeWolfe D., McGann K., Ghofrani J., Geiger E., Helzer C., Kleiboeker S., Jost S., Tan C. Multiple Factors Contribute to an Expanded Immune Risk Profile in Pre Renal Transplant Candidates Am J Transplant. 2017;17 (suppl 3).

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