Human peripheral blood lymphocytes sensitised to PPD respond to in vitro stimulation with increased expression of CD69 and CD134 activation antigens and production of Th-1 type cytokines.

Individuals sensitised to Mycobacterium tuberculosis antigens by infection, vaccination or Mantoux test generate specific memory cells. The response to in vitro restimulation with PPD is observed as the lymphoid cell proliferation and production of Th-1 type cytokines. Cell-mediated immune response was measured by Mantoux test, lymphocyte blast transformation test, estimation of IFN-gamma production (Quantiferon, ELISPOT), and expression of CD69 and CD134 molecules on the T-helper lymphocytes (CD4+). All the methods used were compared for parity of the results. According to Mantoux test results, the patients could be distributed into two groups: responder and non-responder group. Induration in Mantoux test after a new contact with PPD in non-responders was smaller than 5 mm, they produced only small amounts of IFN-gamma, lymphocyte blast transformation was poor, and expression of CD69 and CD134 was low. In responders reaction was much more intensive in all tests measured. We conclude that the reactivity of memory cells to M. tuberculosis antigens can be effectively detected by Mantoux test. The same was true also for the in vitro tests presented but in addition the in vitro tests give more information about the mechanism involved in the immune response against M. tuberculosis.