Previous Article | Next Article ![]()
Infection and Immunity, February 1999, p. 581-588, Vol. 67, No. 2
Departments of
Pathology1 and
Medicine,2 New York Medical College,
Valhalla, New York 10595, and
Pasteur Institute of
Brussels, B-1180 Brussels, Belgium3
Received 20 July 1998/Returned for modification 3 September
1998/Accepted 10 November 1998
Antigen 85 (Ag85) complex proteins are major secretory products of
Mycobacterium tuberculosis and induce strong cellular and humoral immune responses in infected experimental animals and human
beings. We have previously shown that nanogram doses of these 30- to
32-kDa fibronectin-binding proteins inhibit local expression
of delayed hypersensitivity by a T-cell fibronectin-dependent mechanism. Circulating levels of Ag85 might be expected to be elevated
in patients with active tuberculosis and possibly to play a role in
systemic anergy in these patients. To test this hypothesis, Ag85 was
measured in serum and urine by a monoclonal antibody-based dot
immunobinding assay in 56 patients and controls with known skin test
reactivity. Median serum Ag85 levels were 50- to 150-fold higher in
patients with active tuberculosis than in patients with active M. avium-intracellulare disease or other nontuberculous
pulmonary disease or in healthy controls (P < 0.001). The median and range of serum Ag85 in patients with active
tuberculosis was not significantly different between skin test-positive
and -negative subjects. Patients with active M. avium
disease could be distinguished from those with disease due to M. tuberculosis by monoclonal anti-Ag85 antibodies of appropriate
specificities. No increases in urinary Ag85 were detected in any
patient, regardless of the Ag85 level in serum. Chromatographic
analysis and immunoprecipitation studies of serum revealed that Ag85
existed in the serum of these patients complexed to either fibronectin
or immunoglobulin G (IgG). Uncomplexed circulating Ag85 was
demonstrable in serum from fewer than 20% of patients with active
tuberculosis. In patients with active tuberculosis, Ag85 is therefore
likely to circulate primarily as complexes with plasma fibronectin and
IgG rather than in unbound form. The existence of Ag85 complexes with
plasma proteins would account for its lack of urinary clearance.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Pathophysiology of Antigen 85 in Patients with Active
Tuberculosis: Antigen 85 Circulates as Complexes with Fibronectin
and Immunoglobulin G
*
Corresponding author. Mailing address: Department of
Pathology, Basic Science Building, New York Medical College,
Valhalla, NY 10595. Phone: (914) 594-4160. Fax: (914) 594-4163. E-mail: hgodfrey{at}nymc.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»