title: IgG subclass recognition pattern in leprosy: recognition of M. leprae antigens by IgG1 and IgG3 antibodies is distinct across the disease spectrum.
abstract: The recognition of Mycobacterium leprae antigens by IgG subclasses in patients with leprosy was investigated by electrophoresing M. leprae sonicate in SDS-polyacrylamide gel and immunoblotting analysis. Serum pools were used from leprosy patients with either lepromatous (LL/BL) or tuberculoid (BT/TT) disease. A serum pool from healthy controls (EC) was used to determine the baseline antibody activity. To adjust for quantitative differences in antibodies across the disease spectrum, the LL/BL serum pool was used at a 1:200 dilution; the BT/TT serum pool, at 1:20 dilution. Monoclonal antibodies specific for each of the IgG subclasses were used as probes, with anti-mouse IgG conjugated to alkaline phosphatase as the revealing probe. IgG1 antibodies bound to several discrete bands in the range of 10-70 kDa in LL/BL patients, while BT/TT patients showed a more diffuse pattern with the strongest IgG1 antibody binding in the region of 25-40 kDa. Recognition with IgG2 was restricted to a region between 25-36 kDa (which also stained strongly for carbohydrates) in both LL/BL and BT/TT patients. Binding with IgG3 antibodies was more restricted than IgG1 antibodies in LL/BL sera with strong recognition restricted to 25 and 28 kDa. BT/TT sera showed strong binding with IgG3 antibodies in the region of 25-32 as well as 5-7 kDa. IgG4 antibodies showed weak binding to a 28-kDa in lepromatous patients only. The differences in IgG subclass recognition patterns and their implications are discussed.
authors.affiliation: Department of Microbiology, Aga Khan University, Karachi, Pakistan.
authors.forename: A
authors.initials: A
authors.lastname: Kifayet
authors.forename: R
authors.initials: R
authors.lastname: Hussain
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000145:classification* / Q000276:immunology; D007918:Leprosy / Q000276:immunology*; D009166:Mycobacterium leprae / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007074:Immunoglobulin G