Kinetics of circulating antibodies, immune complex and specific antibody-secreting cells in tuberculosis patients during 6 months of antimicrobial therapy

Objective: During the follow-up of a group of patients with active tubercul osis, the predictive potential of several antibody-based assays was evaluat ed in monitoring treatment efficacy. Design: Eleven patients with bacteriologically documented pulmonary tubercu losis and two patients with tuberculosis pleurisy were studied over a perio d of 6 months, from the clay before treatment to its completion. The kineti cs of the humoral response to Mycobacterium tuberculosis was determined by the number of specific circulating antibody secreting cells (ASC) (ELISPOT assay), as well as the titres of specific circulating antibody and specific antibody present in circulating immune complexes (quantitative ELISA). Results: Follow-up ELISPOT assays, performed after initiation of tuberculos is therapy showed a rapid increase of ASC, during the first week, followed by rapid 3-10 fold decline of ASC in 12 of 13 patients tested. This decline occurred more rapidly than the mycobacterial culture conversion. In contra st, follow-up of ELISA assays did not give relevant information in assessin g the outcome of treatment. Conclusion: In comparison with direct detection of tubercle bacilli in sput um samples, the rapid clearance of specific circulating ASC occuring early on after the onset of therapy could suggest a potential usefulness of ELISP OT in monitoring therapeutic response. (C) 2000 Harcourt Publishers Ltd.