Anti-smooth muscle antibody in clinical human and experimental animal Mycoplasma pneumoniae infection.
Autoantibody formation is possibly integral to the development of non-respiratory manifestations of acute Mycoplasma pneumoniae infection. We sought to confirm the occurrence of smooth muscle antibodies (SMA) in humans with acute Myc. pneumoniae respiratory infection and furthermore to assess whether similar autoantibodies would develop in a hamster model of respiratory infection. Paired sera from 21 patients with acute infection were assayed for SMA by immunofluorescence on mouse kidney/stomach substrates. The frequency of SMA was then determined for 52 paediatric patients with acute Myc. pneumoniae infection and 16 controls, and for sera from a hamster model of infection. Five of 21 paired sera had an increment in SMA between acute and convalescent specimens. At a screening dilution of 1:40, 18/52 infected and 0/16 controls had positive sera (P = 0.003); positive specimens demonstrated IgG rather than IgM SMA. In the hamster model of Myc. pneumoniae respiratory infection, significant IgG SMA increases occurred in 7/19 infections but not in 11 controls (P = 0.02). Immunoblotting did not identify actin as the substrate for SMA. Smooth muscle antibody increases are found in a significant minority of Myc. pneumoniae-infected humans and hamsters. A role for SMA in the pathogenesis of Myc. pneumoniae infection remains to be defined.
Cimolai
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Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.
Cheong
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AC
D000293:Adolescent; D000328:Adult; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001323:Autoantibodies / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D006224:Cricetinae; D004195:Disease Models, Animal; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009130:Muscle, Smooth / Q000276:immunology*; D011019:Pneumonia, Mycoplasma / Q000097:blood / Q000276:immunology*
D000907:Antibodies, Bacterial; D001323:Autoantibodies