Evaluation of in vitro assays (lymphocyte proliferation assays, cytokine production assays and/or T spot TBtm and/or Quantiferon-TB Gold) during follow-up of individuals with recent Mantoux skin test conversion, or (latent or clinically active) Tuberculosis.

In case of exposure to contagious pulmonary tuberculosis about 25 to 50% of the
inner family members become infected about 15% develop clinically active
tuberculosis of whom about halve develop contagious pulmonary disease and can
spread the disease further.
The reason why some individuals develop disease (<15%) wheras others remain
healthy (>85%) and contain the outgrowth of Mycobacteria, is uncertain. Likely,
both environmental a well as host genetic fectors play a role in this process,
as do the specifics of the bacteria.

Hypothesis:

- The height of the result of the MTB-specific assays is directly related to
the number of MTB bacilli present. As a result, effective treatment of persons
with LTBI will cause a decrease of the quantitative test result and finally a
negative result of the assays. On the other hand, a rise of the responses to
MTB-specific antigens and low or decreasing responses to latency antigens in
untreated latently infected persons may predict development to active TB disease

Aims of the study:

- The primary aim is to follow-up persons diagnosed with a positive TST result
or latent or clinically active tuberculosis, using In Vitro assays and immune
responses to various latency antigens in order to relate the time course of
test results to 1. the effect of treatment and 2. the prediction of active
TB/surrogate marker of protection.
-Should additional relevant questions arise during the evaluation of het large
dataset that was obtained during the preceding study, these will be presented
to the Ethical Review Board for evaluation.

Prospective cohort study following up TST positieve individuals and individuals
being treated for latent or clinically active Tuberculosis.

Five times venapunction in two years time.