Evaluation of immunity level of B.C.G vaccine against tuberculosis by using skin test for tuberculin and in vitro response of lymphocytes to B.C.G antigens in Shavoor city students

Tuberculin skin test is a screening test for tuberculosis. The aim of this investigation has studied in vitro the immunity level out of Bacillus Calmette–Guerin (BCG) vaccine, through measurement of interferon gamma (IFN γ) in growth medium, in the students of Shavoor city. This research is an experimental study that was performed on 32 male and female students of the three educational levels. After blood sampling, the peripheral blood mononuclear cells were isolated with 5 or 20 μl B.C.G vaccine were co-cultured in CO2 incubator in 37°C for 48 and 72 hours, and IFN γ level measured by the enzyme-linked immunosorbent method. For statistical analyses, independent t-test was used to analyze the differences between the two groups using SPSS software version 23. Analysis of the results showed that there was a significant difference between the size of the induration at different ages of 13 years old (P <0.05). Also, there was no significant difference between the size of the induration in boys and girls (P> 0.05).There was a significant difference between the age, time, and amounts of the bacterium 5 or 20 μL of the B.C.G vaccine used with the level of IFN γsecretion in the two groups (P <0.05). With regard to the results, IFN γ secretion is directly related to the dose of bacteria used and the monocular blood cells of the students and incubation time. Also, the level of IFN γsecretion at younger ages was lower than that at an early age.