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.

CD69 expression on CD4+ T lymphocytes after in vitro stimulation with tuberculin is an indicator of immune sensitization against Mycobacterium tuberculosis antigens.

The expression of the CD69 antigen on CD4 T lymphocytes after in vitro stimulation with purified protein derivative (2 tuberculin units) was used to evaluate the tuberculin reactivities of 52 individuals from four experimental groups: Mycobacterium bovis BCG-vaccinated healthy individuals with a negative tuberculin skin test (TST) result (group A), BCG-vaccinated healthy individuals with a positive TST result (group B), patients with active tuberculosis (TB) before treatment (group C), and individuals with clinically inactive TB who had previously completed a prescribed course of chemotherapy (group D). The expression of CD69 on CD4 T lymphocytes was significantly higher in patients with active TB (16.2%+/-7.3%), individuals with clinically inactive TB (10.5%+/-7.4%), and healthy individuals with a positive TST result (15.5%+/-7.2%) than in healthy individuals with a negative TST result (3.8%+/-4.3%) (P<0.005). We confirmed the correlation between CD69 antigen expression on T lymphocytes after stimulation with tuberculin and the TST induration diameter (Spearman rho=0.783; P<0.001), an assay for gamma interferon (the Quantiferon-TB assay; Spearman rho=0.613; P<0.001), and the lymphocyte BLAST transformation test (Spearman rho=0.537; P<0.001). Our results demonstrate the usefulness of the determination of CD69 on CD4 T lymphocytes after in vitro stimulation with tuberculin as a rapid indicator of immune sensitization against Mycobacterium tuberculosis.