EVALUATION OF LIONEX TB KITS AND FOUR MYCOBACTERIAL ANTIGENS FOR IGG AND IGA DETECTION IN CEREBROSPINAL FLUID WITH NEGATIVE ACID FAST STAINING FROM TB MENINGITIS PATIENTS

Isabela Gama Sardella (FIOCRUZ); Mahavir Singh (LIONEX); Susanne Kumpfer (LIONEX); Rafael Ribeiro Heringer (UFRJ); Maria Helena Feres Saad (FIOCRUZ); Marzia Puccioni Sohler (LIONEX)

To evaluate commercial LIONEX TB ELISA together with four recombinant antigens of M. tuberculosis (MPT-64, MT10.3, 16 kDa and 38 kDa) for IgG and IgA detection in the diagnosis of TB meningitis (TBM) with negative AFB staining cerebrospinal fluid (CSF), 19 cases of TBM, 67 other infectious meningoencefalitis and 73 of other neurological disorder disease (NIND) were tested by ELISA. Among the single antigens tested with the TBM group, only six CSF samples reacted with most of the antigens, but the majority recognized selectively the MPT-64, mainly the IgA isotype (14/19), followed by 38 kDa and 16 kDa antigens primarily for IgG. Four CSF-TBM samples did not react to any of the single antigens tested. These results reflect sensitivity for IgA-MPT-64 of 73.7% and an overall specificity of 96.2%, and addition of other antigen results did not improve this data. By the other hand Lionex IgA kit sowed thelowest sensitivity (16%). While MPT-64 was preferentially recognized by IgA, for 38 kDa and 16 kDa IgG antibodies were present in the CSF with similar sensitivity (31.6% to 36.8%, respectively) with specificity >96.2%. For IgG, cumulative values for MPT64/MT10.3/38kDa increased the sensitivity to 58% (11/19) followed by MPT64/MT10.3 and MPT64/38kDa (10/19, 53%) with specificity <94%. NIND group did not offer cross reactivity except for IgA 38 kDa (2/72, 2.8%). The Lionex IgG kit (78.9%) showed the highest sensitivity and at a specificity of 94.9%. All CSF with high protein concentration were also associated with antibody positivity. CSF/HIV+ patients did not influence the sensitivity of the tests. Our results suggest that both assays are suitable as adjuvant test for TBM diagnosis with negative AFB staining CSF, and to our knowledge, this is the first description of IgA-MPT-64 antibody presence in CSF/TBM. Both tests deserve further large scale clinical evaluations for TBM diagnosis in different settings.