Interesting question as high-altitude medicine is usually about mountain sickness. There are different types of tuberculosis infections - active and latent. Active tuberculosis often show up with pulmonary (i.e. lung) symptoms. There have been reports that high altitudes (and the low oxygen environment) may improve symptoms related to pulmonary TB and possibly even cure it. The research is limited though.
Latent TB, on the other hand, usually means that you were exposed to TB in the past but don't have any active signs of it right now other than being positive on the skin test. Positive TB skin tests are common in healthcare workers and these days it's worth getting a TB blood test to confirm that the TB skin test was even accurate:
https://www.accesalabs.com/QuantiFERON- ... Blood-TestAssuming that you do have a real positive TB test and don't have any active signs of TB in your lungs or elsewhere, the lower oxygen levels at altitude should have no effect on a latent TB infection. Possibly different story if it does turn into an active TB infection at a later date.
Hope that helps!