Purpose: Most centers use interferon gamma release assays (IGRA) to screen for latent TB in transplant candidates. Some of them have an indeterminate result due to lack of lymphocyte response to positive mitogen control. We hypothesize that an indeterminate IGRA result is a surrogate marker for impaired immune function, and thus predict a higher risk of infection and a lower rate of allograft rejection after solid organ transplantation.

Methods: We performed a matched case-control study. We identified 53 transplant recipients with pre-transplant indeterminate IGRA during 2011-2015 using transplant and microbiology databases. Two controls with truly negative screening IGRA were selected as controls and matched based on allograft type, year of transplant, age, and underlying disease. The rationale to match based on these characteristics was to ensure the use of the same protocols for anti-rejection agents and antimicrobial prophylaxis for both the cases and the controls. We compared the incidence of infection and rejection between the two group during the first year after transplantation.

Results: Of the 53 cases 28 (53%) were liver transplant recipients, 8 (15%) were combined liver/kidney, and 10 (19%) were kidney transplant recipients. 21/53 (40%) of cases had at least one episode of acute rejection versus 43/105 (41%) of controls. Similar episodes of subsequent rejection occurred between the two groups, with 18% of cases and 17% of controls having a 2^nd episode. 30/53 (57%) of cases and 59/105 (56%) of controls had at least one infection. However, 21/53 (40%) cases and 14/105 (13%) of controls developed a second infection (p=0.0004).

Conclusion: There was no significant difference in incidence of allograft rejection between those with an indeterminate result for IGRA pre-transplant compared to those with an appropriate response to mitogen control. However, transplant recipients with indeterminate IGRA result may be at an increased risk of developing more infections after transplantation.

CITATION INFORMATION: Zimmer A, Razonable R. Does an Indeterminate Result on Pre-Transplantation Tuberculosis Interferon Gamma Release Assay Predict Risk for Post-Transplantation Infection or Rejection? Am J Transplant. 2017;17 (suppl 3).

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