title: Conjunctival M cells selectively bind and translocate Maackia amurensis leukoagglutinin.
abstract: Antigen-sampling M cells are found in the follicle-associated epithelium above organized lymphoid tissue in many mucosae. They play a key role in initiating the mucosal immune response and act as a site of entry for opportunistic pathogens. This study investigates the presence of M cells in the Guinea pig conjunctiva. Maackia amurensis leukoagglutinin I and II (MAL-I and MAL-II) were identified as potential conjunctival M cell markers based on a screening of 12 lectins and 5 carbohydrate epitope antibodies on aldehyde-fixed follicles. Biotinylated or fluorescein-conjugated MAL-I was then instilled into conjunctival sacs in vivo for 15-60 min. Specimens were assessed by epi-fluorescence stereomicroscopy, confocal scanning laser microscopy and transmission and scanning electron microscopy (TEM and SEM). Selective labelling of a subset of epithelial cells overlying lymphoid follicles was observed following in vivo exposure to MAL-I. MAL-I labelling was restricted to cells with sparse, irregular microvilli. Cells preferentially labelled with MAL-I were found to internalize the lectin during a 60 min in vivo exposure. MAL-I was transcytosed to basolateral membranes of cells filled with intracellular vesicles during a 45 min in vivo incubation. This study demonstrates that the Guinea pig conjunctiva contains a cell with morphological and functional characteristics of antigen-sampling M cells.
authors.affiliation: Division of Biological Sciences, University of Missouri, 3 Tucker Hall, Columbia, MO, USA. ckma8c@mizzou.edu
authors.forename: Carisa K
authors.initials: CK
authors.lastname: Meagher
authors.forename: Hongshan
authors.initials: H
authors.lastname: Liu
authors.forename: Cecil P
authors.initials: CP
authors.lastname: Moore
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Phillips
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003228:Conjunctiva / Q000166:cytology* / Q000276:immunology / Q000648:ultrastructure; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism; D005136:Eye Proteins / Q000276:immunology / Q000378:metabolism; D006168:Guinea Pigs; D037102:Lectins / Q000032:analysis; D008221:Lymphoid Tissue / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D009092:Mucous Membrane / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D010835:Phytohemagglutinins / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D015415:Biomarkers; D005136:Eye Proteins; D037102:Lectins; D010835:Phytohemagglutinins; C100156:leukoagglutinins, plants; D019158:N-Acetylneuraminic Acid