Abstract
The immunoglobulin A (IgA) is produced to defend mucosal surfaces from environmental organisms, but host defenses against the very heavy load of intestinal commensal microorganisms are poorly understood. The IgA against intestinal commensal bacterial antigens was analyzed; it was not simply "natural antibody" but was specifically induced and responded to antigenic changes within an established gut flora. In contrast to IgA responses against exotoxins, a significant proportion of this specific anti-commensal IgA induction was through a pathway that was independent of T cell help and of follicular lymphoid tissue organization, which may reflect an evolutionarily primitive form of specific immune defense.
MeSH terms
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Animals
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Antibody Specificity
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Antigens, Bacterial / immunology
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B-Lymphocytes / immunology*
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Bacterial Proteins / immunology
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Enterobacter cloacae / immunology*
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Escherichia coli / immunology*
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Genes, T-Cell Receptor
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Germ-Free Life
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Immunity, Mucosal*
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Immunoglobulin A, Secretory / biosynthesis*
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Immunoglobulin A, Secretory / immunology
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Intestinal Mucosa / immunology*
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Intestinal Mucosa / microbiology
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Lipopolysaccharides / immunology
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Mice
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Mice, Inbred C57BL
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Peritoneum / cytology
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Plasma Cells / immunology
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Porins / immunology
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Specific Pathogen-Free Organisms
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T-Lymphocytes / immunology*
Substances
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Antigens, Bacterial
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Bacterial Proteins
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Immunoglobulin A, Secretory
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Lipopolysaccharides
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OmpF protein
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Porins