Background

Simple standardized measures of global immunity may help predict the risk of infections post-transplant. The Quantiferon-Monitor (QFM) test is a novel interferon-γ (IFN-γ) release assay that can provide global measure of overall innate and adaptive cell-mediated immune function using antigens for stimulation of whole blood. The objective of this prospective study was to assess whether IFN-γ levels obtained by QFM correlate with infections post-transplant.

Methods

In this prospective observational study, transplant patients had QFM testing performed at 1, 3, and 6 months post-transplant. Clinical data were collected up to one-year post-transplant. The QFM assay involves stimulation of whole blood with a lyosphere containing anti-CD3 and R848 antigens followed by an ELISA for IFN-γ (IU/mL). Levels of IFN-γ were correlated with subsequent infectious complications.

Results

We enrolled 148 patients (liver=50, lung=51, kidney=47). QFM was performed in 109, 67 and 37 patients at month 1, 3 and 6 post-transplant respectively. In paired comparisons, the median IFN-γ level at month 1 (11.7 IU/mL, range 0.0 – 818.9 IU/mL) was significantly lower compared to month 3 (25.3 IU/mL, range 0.0 – 1605.6 IU/mL, p<0.001) and month 6 (36.8 IU/mL, range 0.4 – 1393.1 IU/mL, p<0.001). IFN-γ levels of lung transplant recipients were significantly lower compared to non-lung transplant recipients (month 1: 5.0 vs. 21.7 IU/mL, p=0.002). During the follow-up period (median 334 days), there were 105 episodes of infection in 40 patients (20 UTI, 21 pneumonias, 13 bacteremia, 37 viremia and 14 other). At month 1, IFN-γ levels were 15.7 vs 4.4 IU/mL in those with no subsequent infection vs. infection (p=0.023). Similarly, at month 3, IFN-γ levels were 33.3 vs. 14.5 IU/mL respectively (p<0.001). At month 6, IFN-γ levels tended to be lower in patients with infections (55.4 vs. 18.6 IU/mL, p=0.21). Among patients that developed CMV viremia specifically, IFN-γ levels were significantly lower compared to non-viremic patients at month 1(2.5 vs 18.8 IU/mL, p=0.001), but not month 3 (7.1 vs 25.4 IU/mL, p=0.054) or month 6 (15.3 vs 30.4 IU/mL, p=0.12).

Conclusion

We evaluated a novel method of monitoring post-transplant global immune function including both innate and adaptive arms. This assay may help determine the degree of immunosuppression and predict infections in transplant recipients.

CITATION INFORMATION: Mian M, Humar A, Keshwani S, Husain S, Ashton P, Han S, Singer L, Kim J, Renner E, Bhat M, Kumar D. Evaluation of a Novel Global Immunity Assay to Predict Infections in Organ Transplant Recipients. Am J Transplant. 2016;16 (suppl 3).

« Back to 2016 American Transplant Congress