The Evaluation Of Detecting The Mycobacterial Antigens In Monocyte Of The Cerebrospinal Fluid To The Diagnosis Of Tuberculous Meningitis

Objective The incidence of tuberculosis (TB) is increasing in recent years due to various factors, such as the prevalence of multiple-drug resistance tubercu- losis, the infection of human immunodeficiency virus and the poverty. Although most of the infected persons initiate self-protective cell-mediated immune reacti- on to prevent them against active tuberculosis, TB is still one of the most fatal infectious diseases. TB involvement of central nervous system accounts for 5% of all extrapulmonary TB. Due to its high fatality and disability, tuberculous menin- gitis (TBM) is one of the most serious complications of TB. Because of the disad- vantages of the present methods, there are still no viable methods which meet the clinical demands. TB is a kind of the parasitic bacterium and usually parasitizes in its host, mononuclear macrophage once invading the human body. In the infec- ted living body, it is the mycobacterial antigens instead of mycobacterial antibody that emerged in the organism at first. The mycobacterial antigens are not affected by the immune state of the host. In the present study, three different antibodies are used to detect the tubercular antigens in the mononuclear macrophages in CSF and PB. The purpose of this study is to estimate the value of the three anti- gens in the diagnosis of TBM.Methods Immunocytochemistry was used to detect PPD,38KD and Ag85B antigens, and percentages of the positive cells in the mononuclear macrophages in CSF and PB of the 55 TBM and 48 the other central nervous system infections were counted. All the data were analyzed by SPSS 13.0. Morphology of mono- nuclear macrophages in the TBM and control group Immunofluorescence was observed under the laser scanning confocal microscope.Results 1).The percentage of the positive cells in CSF and PB of TBM was much higher than that of the control group (P<0.01); 2). In CSF, the sensitivity of the PPD, 38KD, Ag85B antibodies to diagnosis TBM was 87.3%, 89.1% and 94.5%, respectively, and the specificity is 79.1%, 91.7% and 52.1%, respectively; 3). In PB, the sensitivity of the PPD, 38KD, Ag85B antibodies to diagnosis TBM was 36.4%, 43.6% and 54.5%, respectively, and the specificity is 81.3%, 87.5% and 83.3%, respectively. 4). No differences were found among the percentage of the positive cells with the three antigens in CSF of TBM within one month (P>0.05); In TBM patients with different pathogenetic condition, there was no difference of the percentage of the positive cells of the three antigens (P>0.05); There was a close correlation between the first and the second CSF of the same patient (P<0.01); 5. PPD-/38KD-positive cells in PB of TBM combining with extra-intracranial TB were higher than that of TBM alone (P<0.05), and Ag85B-positive cells had no difference between the two groups.Conclusion Immunocytochemistry of 38KD is a simple method with high sensitivity and specificity which can be used for the diagnosis of TBM. However, Ag85B shows a relative low specificity. It is more sensitive to detect the antigen in CSF in the diagnosis of TBM than in PB. In TBM group there is a close corre- lation between antituberculosis treatment and the percentage of the positive cells of the three antigens in CSF, while the percentage has little relationship with both the course of disease and the pathogenetic condition.