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 tuberculosis, the predictive potential of several antibody-based assays was evaluated in monitoring treatment efficacy.

DESIGN

Eleven patients with bacteriologically documented pulmonary tuberculosis and two patients with tuberculosis pleurisy were studied over a period of 6 months, from the day before treatment to its completion. The kinetics 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 tuberculosis 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 contrast, follow-up of ELISA assays did not give relevant information in assessing the outcome of treatment.

CONCLUSION

In comparison with direct detection of tubercle bacilli in sputum samples, the rapid clearance of specific circulating ASC occurring early on after the onset of therapy could suggest a potential usefulness of ELISPOT in monitoring therapeutic response.