The distribution of lymphoid cells in the small intestine of germ-free and conventional piglets

Dev Comp Immunol. 2015 Jul;51(1):99-107. doi: 10.1016/j.dci.2015.02.014. Epub 2015 Mar 2.


Porcine ileum is populated with a high proportion of B cells but previous studies have shown that they are not developed there. While B cells prevail in the ileum even in germ-free animals, microbial colonization is a major factor that causes even a greater prevalence of B cells in the ileum and further differential representation of lymphoid cells throughout small intestine. Analysis of lymphoid subpopulations showed that the effector cells appear only after colonization. These include class-switched IgM(+)IgA(+) B cells, primed CD2(-)CD21(+) B cells, antibody-producing/memory CD2(+)CD21(-) B cells, and effector/memory CD4(+)CD8(+) αβ Th cells. While colonization resulted in a uniform distribution of effector cells throughout the gut, it caused a decrease in the frequency of cytotoxic αβ and CD2(+)CD8(+) γδ T cells. These results suggest that the ileum is a site where naive B cells expand presumably to increase antibody repertoire but the entire small intestine is immunofunctionally comparable.

Keywords: Cell surface molecules; Differentiation; Gut development; Lymphocyte subpopulations; Mucosal immunity; Porcine immune system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / metabolism
  • B-Lymphocyte Subsets / immunology*
  • B-Lymphocyte Subsets / microbiology
  • B-Lymphocytes / immunology*
  • B-Lymphocytes / microbiology
  • Bacteria / growth & development
  • Bacteria / immunology
  • Germ-Free Life / immunology
  • Ileum / immunology*
  • Ileum / microbiology
  • Immunoglobulin Class Switching
  • Immunologic Memory
  • Immunophenotyping
  • Lymphocyte Activation
  • Microbiota / immunology
  • Receptors, Antigen, T-Cell, alpha-beta / metabolism
  • Receptors, Antigen, T-Cell, gamma-delta / metabolism*
  • Sus scrofa / immunology*
  • T-Lymphocytes, Cytotoxic / immunology*
  • T-Lymphocytes, Cytotoxic / microbiology
  • T-Lymphocytes, Helper-Inducer / immunology*
  • T-Lymphocytes, Helper-Inducer / microbiology


  • Antigens, CD
  • Receptors, Antigen, T-Cell, alpha-beta
  • Receptors, Antigen, T-Cell, gamma-delta