The enigma of the lower gut-associated lymphoid tissue (GALT)

Abstract

Artiodactyls possess GALT that appears in fetal life and is located at the extreme end of the ileum. These IPP contain mostly B cells and involute early in postnatal life. Rabbits have a similarly located lymphoid organ, called the sacculus rotundus. Studies in sheep and rabbits have led to the concept that the lower hindgut GALT represents primary lymphoid tissue for B cells and is necessary for normal B cell development, analogous to the bursa of Fabricius. This review traces the history of the observations and theories that have led to the existing concept concerning the role of lower GALT. We then review recent data from piglets with resected IPP that challenges the concept that the IPP is primary B cell lymphoid tissue and that artiodactyls and rabbits are members of the GALT group in the same context as gallinaceous birds. Eliminating the IPP as the primary lymphoid tissue for B cells leads to the hypothesis that the IPP acts as first-responder mucosal lymphoid tissue.

B Cell Lymphogenesis in Swine Is Located in the Bone Marrow

“…However, pigs, together with all other ungulates, were speculated for .30 y to belong to species that use ileal Peyer's patches for development of B cells (10,11,25). We have previously shown that ileal Peyer's patches are not required for B cell development and maintenance (12)(13)(14), and that this role has probably been filled by the BM (26)(27)(28)(29)(30). In the present study we have finally shown that B cell lymphogenesis in pigs clearly occurs in the BM.…”

“…These species use specialized GALTs located in a hindgut, and include gallinaceous birds that use the bursa of Fabricius, rabbits that use the sacculus rotundus, and ungulates, including swine, that use ilealthis categorization by showing that at least in swine (and probably in other ungulates), ileal Peyer's patches are not a significant source of B cells, are not required for maintenance of the systemic B cell pool, and are not a site of primary B cell lymphogenesis (12)(13)(14). The results of the present study extend those studies by showing that porcine B cells are developed throughout life in the BM, the primary lymphoid organ also for mice and humans (2,3).…”

The Histogenesis of the Third Pathway of Colonic Carcinogenesis in Rats

“…Several authors described colonic GALT follicles to be covered by a mucosal lining having epithelial cuboidal cells, few or no goblet cells, M cells, and a subjacent primary lymphoid aggregate (without or with germinal centres) (15)(16)(17). In addition, colonic crypts with eosinophilic cytoplasm having few or no goblet cells were found here interspersed in the cuboidal epithelium in DMH-treated rats.…”

The comparative profile of lymphoid cells and the T and B cell spectratype of germ-free piglets infected with viruses SIV, PRRSV or PCV2

“…The diversity in the B and αβ T cell repertoires is overwhelmingly determined by the diversity in CDR3 (IGHV-CDR3 and TCRBV-CDR3 respectively) [38][39][40][41]. Thus, length analyses of CDR3 regions using polyacrylamide sequencing gels provides a clonotypic analysis of porcine B cells [39][40][41][42] and αβ T cells [43] showing their level of clonality.…”

“…The proportions of individual CD2/CD21 B cell subpopulations were detected from gated IgM + lymphocytes (C). According to our recent studies [25,26,38] …”