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Abstract
Tuberculosis (TB) remains a major cause of morbidity and mortality, and represents the most frequent cause of death by a single infectious agent worldwide.
In many areas of the world, TB remains the most common cause of pleural effusions in the absence of demonstrable pulmonary disease.
Patients with tuberculous pleuritis tend to be underreported because their mycobacterial cultures are frequently negative.
The present study was conducted on forty patients, they were classified according to their f inal diagnosis into four groups:
Group A :
Consists of ten patients had tuberculous pleural effusions based on histopathological and/or bacteriological examination.
Group B :
Consists of ten patients had malignant pleural effusions based on histopathological and/or cytological examination.
Group C :
Consists of ten patients had pleural effusions secondary to infectious causes ( e.g. pneumonia, lung abscess & empyema) diagnosed by clinical presentation, bacteriological examination and radiological findings.
Group D :
Consists of ten patients diagnosed of had transudative pleural effusions based on chemical examination (as a control group).
Measurement of interferon gamma and adenosine deaminase in both pleural samples and blood serum samples was done.
All data were collected and statistically analyzed.
from the present study, the following results were obtained:
There was highly significant statistical difference between different studied groups as regard ¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬IFN-γ marker in both pleural and serum samples and ADA marker in pleural samples but there was non significant stastistical difference as regard ADA marker in serum samples.
There was non significant statistical correlation between IFN-γ and ADA as regard both pleural and serum samples in group A (Tuberculous group).
The best cut-off value for ¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬IFN-γ in pleural samples was:
49.5 Pg/ml
The best cut-off value for ¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬IFN-γ in serum samples was:
10 Pg/ml
The best cut-off value for ADA in pleural samples was:
14.5 U/L
The best cut-off value for ADA in serum samples was:
18.5 U/L
¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬IFN-γ in pleural fluid had the best sensitivity (100 %), specificity (98.7 %) and accuracy (97.5 %) for differentiation between tuberculous pleural effusion and other different types of pleural effusion as compared to ADA in pleural fluid which had sensitivity (100 %), specificity (70 %) and accuracy (77.5 %).
¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬IFN-γ in serum had higher sensitivity (80 %), specificity (90 %) and accuracy (87.5 %) for differentiation between tuberculous pleural effusion and other different types of pleural effusion as compared to ADA in serum which had sensitivity (60 %), specificity (66.7 %) and accuracy (65 %).
There was highly statistical significant difference between group A (Tuberculous group) and all other groups as regard the frequency of positivity of IFN-γ in pleural samples, IFN-γ in serum samples and ADA in pleural samples but there was non statistical significant difference as regard the frequency of positivity of ADA in serum samples.
There was highly statistical significant difference within group A (Tuberculous group) between positive values (above cutoff value) and negative values (below cutoff value) as regard IFN-γ pleural values, IFN-γ serum values and ADA pleural values but there was non statistical significant difference as regard ADA serum values.
from the present study, it is concluded that:
1- IFN-γ is more sensitive, specific and accurate than ADA for diagnosing tuberculous pleural effusion.
2- IFN-γ and ADA are non invasive, simple and quicker diagnostic tools laboratories compared to conventional diagnostic methods. So when these tests are used more routinely, they will have more advantages for the patients and doctors.
3- Measurement of IFN-γ and ADA may decrease the number of patients in whom antituberculous treatment is initiated without confirmation of the tuberculous etiology of the pleural effusion.
4- The histological and microbiological evaluations of pleural tissue samples (Gold standard) are necessary to reliably estimate the potential usefulness of a new diagnostic methods (IFN-γ, ADA, IL-1, IL-6, IL-8, IL-10, IL-12, IL-18, soluble IL-2 receptor, TNF-α, immunosuppressive acidic protein ”IAP”) in patients with tuberculous pleural effusions. In our study percutaneous pleural biopsy was the most common procedure used for this purpose.
5- The IFN-γ determination may be particularly helpful in certain clinical settings, such as in empyema, where ADA measurement was falsely positive. This was the case in five of our patients included in group C (Inflammatory group), with empyema, the ADA activity was markedly elevated while IFN-γ levels were below the cut-off value (49.5 Pg / ml) except for one case which was above the cut-off value.
6- The level of IFN-γ in tuberculous pleural effusion was higher than serum which was due to migration of lymphocytes producing IFN-γ to the site of active disease in pleural space.