Immunoglobulin A protease is a virulence factor for gram-negative pneumonia.
BACKGROUND
Secretory immunoglobulin A (SIgA) is the principal immunologic defense of respiratory and other mucosal surfaces in the body. SIgA is relatively stable in mucosal secretions. However, cleavage of SIgA by bacterial proteases might render it immunologically inactive and thus contribute to the development of pneumonia as well as other infections. Bacterial species and infection sites might be important in the expression of bacterial protease activity and serve as the impetus to this study.


METHODS
Bacterial isolates from respiratory and nonrespiratory sites were incubated with SIgA in vitro. SIgA degradation was determined by size exclusion ultrafiltration and gel electrophoresis.


RESULTS
IgA protease activity was evident in gram-negative but not gram-positive respiratory isolates. Gram-negative isolates from nonrespiratory sources did not exhibit IgA protease activity.


CONCLUSIONS
Expression of IgA protease activity might be important in the development and subsequent outcome of gram-negative pneumonia in the patient in the surgical intensive care unit.
Department of Surgery, Wayne State University, Detroit, MI 48201, USA.
Lawrence N
LN
Diebel
David M
DM
Liberati
Alfred E
AE
Baylor
William J
WJ
Brown
John
J
Devlin
D001426:Bacterial Proteins / Q000276:immunology*; D006090:Gram-Negative Bacteria / Q000276:immunology / Q000472:pathogenicity*; D016905:Gram-Negative Bacterial Infections / Q000276:immunology*; D006801:Humans; D018410:Pneumonia, Bacterial / Q000276:immunology*; D020545:Respiratory Mucosa / Q000503:physiopathology; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000276:immunology*; D037521:Virulence Factors / Q000276:immunology*
D001426:Bacterial Proteins; D037521:Virulence Factors; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase