As the QFT-G indeterminate rate was high for HIV patients with CD4+ T cell count less than 50/μL as seen above, we analyzed the relationship between CD4+ T cell count and level of responses to the test's positive control (stimulation with mitogen) for a total of 95 patients excluding those with TB (n = 9) or M. kansasii disease (n = 1) and those with negative control response being higher than positive control response (n = 2). Here, CD4 is linked to tuberculosis.