β1 integrins are not required for the maintenance of lymphocytes within intestinal epithelia

Abstract

β1 integrins are thought to play a central role in maintaining lymphocytes within mucosal epithelia via their interactions with extracellular matrix proteins and subepithelial cellular components within and underlying the basement membrane. In the current study type a (CD8αβTCRαβ) and type b (CD8ααTCRγδ and CD8ααTCRαβ) intraepithelial lymphocyte (IEL) subsets within the mouse small intestine were found to express functional β1 integrin and the β1 integrin α chain partners α1, α 2, and α4. Using inducible β 1 integrin-knockout bone marrow-chimeric mice we demonstrate that IEL expression of α1 and α 2 but not α4 is dependent on expression of the β1 chain. Importantly, deletion of the β1 chain in IEL did not alter the number or composition of lymphocytes within the intestinal epithelium. Thus, while IEL express functional β1 integrins, these are not required to maintain lymphocytes within intestinal epithelia. This result is discussed in the light of conventional views of intestinal lymphocyte homing and localization. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.