What is the interpretation of two IGRAs with negative mitogen wells, in the absence of immunosuppression?  

A patient on meloxicam for LBP developed high, persistent fevers and no other symptoms. An IGRA, among many tests, was sent. The IGRA’s mitogen well was negative (the TB and nil wells were negative as well). 8 days later, the IGRA was repeated, and again, all wells, including the mitogen well, were negative.

Does the fact that her PBMC, when exposed to a mitogen, on two separate tests done 8 days apart by a large, commercial lab means that:

1. The lab mishandled her PBMC twice.
2. Something is wrong with her cellular immune system.
3. Other.

A patient, who was epidemiologically at risk for prior TB infection, had an IGRA prior to receiving immunosuppressive chemotherapy. The nil and mitogen wells did not produce significant amounts of IFN-γ, but her TB wells did. The lab interpreted this test as indeterminate. A follow-up test was not sent. How should this result be interpreted? Of relevance, at this time, the patient was receiving chemo, had markedly elevated WBC and fever of unknown origin.

1. TB therapy should be started empirically.
2. This result is not evidence of prior TB infection.
3. Despite recent chemo, the IGRA should be repeated.
4. Need more information.
5. Other.