Diagnostic value of specific immune complexes in detection of active tuberculosis infection

Abstract

The diagnostics of tuberculosis infection, including immunological methods, evolved significant changes over time. Introduction of new diagnostic tests allowed to improve the diagnosis of latent tuberculosis infection (LTI). However, positive results of immunological tests in both tuberculosis patients and in those with LTI do not allow to differentiate between these conditions, thus requiring development and implementation of new diagnostic approaches. A prospective study enrolling two groups of patients was conducted as follows: group I (n = 50) included patients with verified pulmonary tuberculosis, MBT (+), whereas group II (n = 15) consisted of subjects with LTI, and control group was represented by healthy subjects (n = 14). The entire examination protocol included clinical, radiological, bacteriological, and immunological methods (Mantoux test with 2 TU, T-SPOT.TB, QFT and Diaskin test). Immune complexes were determined in all patients and healthy individuals by means of dynamic light scattering after the in vitro addition of specific antigens (ESAT-6 and SFP-10 peptides). The data obtained have shown low informativity of clinical methods in diagnostics of pulmonary tuberculosis. In the presence of characteristic X-radiographic changes, bacteriological verification of tuberculosis was proven only in 46% of cases. Usage of various immunological tests allowed to obtain positive results in 84-90% of cases, along with 100% positivity in subjects with LTI. Detection of specific immune complexes by the method of dynamic light scattering allows to determine the activity of tuberculosis infection in 100 % of cases, and to identify the high-risk group for development of active tuberculosis among the subjects with latent tuberculosis infection. Conclusions: the obtained data may be applied both for diagnosis of active tuberculosis in the absence of verified diagnosis, but also enable identification of a high-risk group for development of the disease in subjects with latent tuberculosis infection.