Identification of myelin basic proteins in circulating immune complexes associated with lepromatous leprosy.
Circulating immune complexes (CIC) were first measured in lepromatous patients (LL) by the 125I-C1q binding assay and the polyethylene glycol (PEG) precipitation test. High levels were found by both methods (95 and 90% of positives, respectively). LL-CIC were investigated for the presence of neural antigens. CIC were precipitated in 3.5% PEG, filtered through protein A-Sepharose affinity chromatography, eluted with glycine-HCl, pH 2.8, and washed with PBS; fractions after CIC dissociation were studied by SDS-PAGE and Western blotting. The LL-CIC PEG precipitates and the glycine-HCl eluates were positive in 76 and 71% respectively against anti-myelin basic proteins (MBP) monoclonal antibody, showing a single band at 15-25 kDa similar to the one obtained incubating MBP with anti-MBP. No reaction was detected with CIC-PBS fractions; strips were incubated with other anti-neural antibodies such as anti-glial fibrillary acidic proteins, anti-S-100, and anti-neurofilaments, without any reactivity. Our results demonstrate that LL-CIC contain MBP as an antigen; its significance could be related to the pathogenesis of leprosy since the liberation of MBP after Mycobacterium leprae nerve damage may elicit anti-MBP autoantibodies to myelin breakdown, which reacts with peripheral nerve MBP inducing CIC formation. This mechanism may be important in demyelination and destruction of nerve in leprosy.
Córsico
B
B
Centro de Investigaciones Immunológicas Básicas y Aplicadas (CINIBA), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
Croce
M V
MV
Mukherjee
R
R
Segal-Eiras
A
A
D000936:Antigen-Antibody Complex / Q000737:chemistry*; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D015440:Leprosy, Lepromatous / Q000097:blood* / Q000276:immunology; D004676:Myelin Basic Protein / Q000097:blood*
D000936:Antigen-Antibody Complex; D004676:Myelin Basic Protein