title: Levels of antibody, free antigen and immune-complexed antigen by ELISA in different grades of sputum positive patients of pulmonary tuberculosis.
abstract: The ES-31 (31 kDa protein) antigen was isolated from culture filtrate of Mycobacterium tuberculosis H37Ra and was shown to have potential in immunodiagnosis of pulmonary tuberculosis. Serum samples from 38 confirmed sputum positive pulmonary tuberculosis patients were grouped into AFB+, AFB++, AFB+++ based on sputum bacillary load. Analysis of tubercular antibody, circulating free and immune complexed antigen (CIC-Ag) was done in serum samples by Indirect and Sandwich ELISA using ES-31 antigen and affinity purified anti ES-31 antibody respectively. The analysis of Geometric mean titre (GMT) of all the three groups showed that GMT of tubercular antibody was considerably decreased compared to elevated levels of CIC-Ag (Antibody: 1360 to 816 and CIC-Ag: 534 to 1744) from low bacillary sample to high bacillary samples, whereas there is no significant change in the titre of circulating free antigen. Low levels of detectable antibody is observed possibly due to removal of antibody from circulation by immune complex formation as confirmed by its elevated levels in sputum AFB+++ positive patients.
authors.affiliation: Department of Biochemistry, Jamnalal Bajaj Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, Maharashtra.
authors.forename: Niraj
authors.initials: N
authors.lastname: Shende
authors.forename: Sonika
authors.initials: S
authors.lastname: Gupta
authors.forename: Satish
authors.initials: S
authors.lastname: Kumar
authors.forename: B C
authors.initials: BC
authors.lastname: Harinath
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis*; D000936:Antigen-Antibody Complex / Q000032:analysis*; D000942:Antigens, Bacterial / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D013183:Sputum / Q000276:immunology* / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000936:Antigen-Antibody Complex; D000942:Antigens, Bacterial