Cryptopatches and Isolated Lymphoid Follicles: Dynamic Lymphoid Tissues Dispensable for the Generation of Intraepithelial Lymphocytes

Eur J Immunol. 2005 Jan;35(1):98-107. doi: 10.1002/eji.200425432.

Abstract

In comparison to secondary lymphoid organs, gut-associated lymphoid tissues such as isolated lymphoid follicles (ILF) and cryptopatches (CP) have been less intensively studied. To gain a better insight into processes regulating organization and function of these structures, which are believed to participate in immune responses and extrathymic T cell development, we characterized the lymphoid structures of the murine small intestine in more detail. The size and cellular composition of small intestinal lymphoid aggregations were analyzed in C57BL/6 and BALB/c wild-type and lymphotoxin (LT)-deficient mice, by flow cytometry, histology and automated multi-color immunofluorescence microscopy evaluating large coherent areas of the intestine. These evaluations demonstrate that aggregated lymphoid structures in the small intestine vary in size and cellular composition, with a majority of structures not matching the current definitions of CP or ILF. Accordingly, significant variations depending on species, age and mouse strain were observed. Furthermore, small bowel transplantation revealed a rapid exchange of B but not T cells between host and grafted tissue. Moreover, LT-deficient animals lack any intestinal lymphoid aggregations yet possess the complete panel of intraepithelial lymphocytes (IEL). In summary, our observations disclose intestinal lymphoid aggregations as dynamic structures with a great deal of inborn plasticity and demonstrate their dispensability for the generation of IEL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Epithelium / anatomy & histology
  • Epithelium / immunology
  • Humans
  • Intestine, Small / anatomy & histology
  • Intestine, Small / cytology
  • Intestine, Small / immunology
  • Lymphocytes / cytology*
  • Lymphocytes / immunology
  • Lymphoid Tissue / anatomy & histology*
  • Lymphoid Tissue / cytology
  • Lymphoid Tissue / immunology
  • Lymphotoxin-alpha / deficiency
  • Lymphotoxin-alpha / genetics
  • Lymphotoxin-beta
  • Membrane Proteins / deficiency
  • Membrane Proteins / genetics
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Phenotype
  • Rats
  • Species Specificity
  • Swine

Substances

  • LTB protein, human
  • Ltb protein, mouse
  • Ltb protein, rat
  • Lymphotoxin-alpha
  • Lymphotoxin-beta
  • Membrane Proteins