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Effect of Fibronectin on IgA-Mediated Uptake of Type III Group B Streptococci by Phagocytes
Kuender D. Yang, John F. Bohnsack, Margaret M. Hawley, Nancy H. Augustine, William A. Knape, Marianne L. Egan, David G. Pritchard and Harry R. Hill
The Journal of Infectious Diseases
Vol. 161, No. 2 (Feb., 1990), pp. 236-241
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/30126082
Page Count: 6
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Previous studies have shown that a type-specific IgA monoclonal antibody alone or in combination with fibronectin (Fn) enhances protective efficacy in two animal models of group B streptococcal infection. To investigate the mechanisms by which IgA mediates protection, the effects of Fn on phagocytosis of group B streptococci (GBS) opsonized with a type Ill-specific IgA monoclonal antibody were examined. Specific IgA alone or in combination with Fn did not promote the phagocytosis of GBS by polymorphonuclear leukocytes (PMNL). Fibronectin also had no significant effect on phagocytosis of IgA-opsonized GBS by monocytes. Specific IgA alone promoted phagocytosis of GBS by culture-derived macrophages in a dose-dependent fashion. Fibronectin enhanced macrophage uptake of the GBS opsonized in a suboptimal concentration of specific IgA (phagocytic index = 2.32 ± 0.56 vs. 3.26 ± 0.48 with Fn; P < .05). These data suggest that protection against GBS in neonatal rats by a combination of Fn and specific IgA is mediated by macrophages rather than by PMNL or monocytes. Fibronectin may have a critical role in host defense at sites where IgA and macrophages predominate.
The Journal of Infectious Diseases © 1990 Oxford University Press