The amount of secreted IgA may not determine the secretory IgA coating ratio of gastrointestinal bacteria

Takeshi Tsuruta, Ryo Inoue, Iyori Nojima, Takamitsu Tsukahara, Hiroshi Hara, Takaji Yajima

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)


It is reported that some, but not all, bacteria in human faeces are coated with secretory immunoglobulin A (S-IgA). We evaluated the proportion of S-IgA-coated bacteria to total intestinal bacteria (S-IgA coating ratio) in the gastrointestinal tract of two different strains of mice supplied by two different suppliers. The S-IgA coating ratio was significantly different in each gastrointestinal segment and between mouse suppliers. The amount of non-bacteria-bound IgA (free IgA) in each gastrointestinal segment indicated that this difference in the S-IgA coating ratio might not be due to the amount of secreted IgA. Furthermore, immunoblotting analysis revealed that only a small amount of IgA (<5% to free-IgA) was used for the coating. This indicates that, although sufficient S-IgA was secreted to coat the entire intestinal population of bacteria, only some part of the bacteria were coated with S-IgA. This study suggests that the amount of luminal S-IgA may not determine the S-IgA coating ratio, and that the amount of IgA coating intestinal commensal bacteria is very small.

Original languageEnglish
Pages (from-to)185-189
Number of pages5
JournalFEMS Immunology and Medical Microbiology
Issue number2
Publication statusPublished - Jul 2009
Externally publishedYes


  • Commensal intestinal bacteria
  • IgA concentration
  • Secretary immunoglobulin A

ASJC Scopus subject areas

  • Immunology and Allergy
  • Microbiology
  • Immunology
  • Microbiology (medical)
  • Infectious Diseases


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