Abstract: Objective  To investigate the cytological changes of cerebrospinal fluid in tuberculous meningitis patients with different positive rates of antipurified protein derivative of tuberculin (PPD) antibody, and further to evaluate their correlation and diagnostic value. Methods  The antiPPD antibody IgG and cytology of cerebrospinal fluid in 26 tuberculous meningitis patients and 30 cases of viral meningitis in the control group were detected at the 1st, 2nd, 3rd and 4th week of onset. Results   At the early stage of onset, tuberculous meningitis patients of the positive rate of antiPPD antibody IgG and the plasmacyte ratio of cerebrospinal fluid cytology were low within the 1st week, while these rates increased during the 2nd to 3rd week. After effective treatment, although the positive rate of antiPPD antibody IgG was still high, the plasmacyte ratio decreased and even disappeared. Cerebrospinal fluid (CSF) anti PPD antibody IgG was negative at the 1st ,2nd, 3rd and 4th week of onset in CSF group. Lymphocyte reactivity was dominant in CSF cytology, and the rate of plasma cell was low. Conclusion  There is better correlation between antiPPD antibody IgG and plasmacyte ratio in cerebrospinal fluid, which represents as low positive rate of antiPPD antibody IgG accompanies with low or no plasmacyte ratio, while high positive rate of antiPPD antibody IgG accompanies with high plasmacyte ratio, the combination of both examinations could improve the early diagnosis rate of tuberculous meningitis.

Key words: tuberculosis, , meningeal, purified protein derivative, antibody, cerebrospional fluid cytology