Viability of Interferon-β Supplemented Human Dendritic Cells after Infection with Mycobacterium Tuberculosis and Bovis

Abstract

Summary T uberculosis is an ancient disease, caused mainly by Mycobacterium tuberculosis, which was identified and described at 1882 by Robert Koch. One third of the world population is infected with T.B. In 2014, there were an estimated 9.6 million new T.B cases & 13 million prevalent cases globally. WHO considered Egypt one of the high burden countries for TB infection with 15 incidence (per 100,000 people). Tuberculosis infection may be asymptomatic (Latent tuberculosis infection) or T.B disease.people suspected of having T.B disease should be referred for complete medical evaluation. Existing methods for detection of Mycobacterium tuberculosis range from simple microscopy & slow culture methods to advanced molecular assays. Tuberculosis is still a leading cause of death worldwide, despite the availability of BCG vaccine & antibiotic treatment. Meta-analysis of BCG vaccination clearly indicated that BCG confers some protection against pulmonary and disseminated T.B in children, principally miliary disease and meningitis, but it is unreliable against the pulmonary T.B in adults. As BCG provides variable protective efficacy, there is an urgent need to develop a vaccine more protective than it. Thus, investigating the impact of BCG infection on the immune response is instrumental for setting a new, effective vaccine. Dendritic cells play a critical role in initiating and regulating a protective T cell response against the pathogens, the comprehension of mycobacterium induced modulation of DC functions is critical to pinpoint new, immunological strategies. In the present study, we investigated whether the exogenous addition of IFN-β (a cytokine that exerts important effects on the immune system) could enhance the response of DC to M.bovis (simulating BCG) infection. Also, due to the role played by DC in initiating and regulating a protective T cell response against Mycobacterium tuberculosis, we sought to compare the effect induced by the infection of human DC with M.bovis (before & after IFN- β) and Mycobacterium tuberculosis on the DC viability. Our study tested the viability of 20 samples of mononuclear DC before & after inoculation with M.bovis (with & without IFN –β pretreatment) & M T.B by using light microscopic examination &trypan blue exclusion method. The viability of DC was evaluated in DC before and after pretreated for 4 h with 200 pM IFN- β (before BCG Infection). Our results revealed that the viability of DC before IFN-β was 75.7% & after IFN -β was 60.7%.This revealed that IFN –β pretreatment didnot improve the viability of DC.