The MHC-related protein 1 (MR1) is expressed by a subpopulation of CD38+, IgA+ cells in the human intestinal mucosa
Beatriz Gozalbo-López1, Manuel Gómez del Moral2, Yolanda Campos-Martín1, Fernando Setién1, Paloma Martín3, Carmen Bellas3, José R. Regueiro1 and Eduardo Martínez-Naves1
1Immunology Unit, School of Medicine, Complutense University, Madrid, Spain, 2Cell Biology Department, School of Medicine, Complutense University, Madrid, Spain and 3Molecular Pathology Laboratory, Pathology Department, Hospital Universitario Puerta de Hierro, Madrid, Spain
M.G. del M. and B.G.-L. contributed equally and are both first authors.
Offprint requests to: Dr. Eduardo Martínez-Naves, Unidad de Inmunología, Facultad de Medicina, Universidad Complutense, Avda. Complutense s/n. 28040 Madrid, Spain. e-mail: emnaves@med.ucm.es
Summary. MHC-related 1 (MR1) molecule is a non-classical member of the MHC class I family of proteins. The sequence homology between classical MHC class I molecules and MR1 is very high, although the MR1 gene is not polymorphic and is highly conserved between species. MR1 is the restriction molecule of a sub-population of T lymphocytes, which are CD4-,CD8- and display conserved TCR α chain. The function of these cells is currently unknown, but they are believed to have regulatory properties similar to those of the CD1d restricted NKT cells
The MR1 gene is ubiquitously transcribed; however it is unknown what types of cells express the MR1 protein “in vivo”. In the present work we analyzed the expression of the MR1 protein using specific antisera and monoclonal antibodies in different human cell lines, in primary cells and in mucosal tissues. We found some lymphoid cell lines that express MR1 on the cell surface but at levels much lower than the MR1 transfected cell lines. In addition, we observed that expression of MR1 in the mucosa is restricted to a subpopulation of plasma cells or plasmablasts, CD38+ or CD138+ and IgA+, located in the human intestinal mucosa. This suggests a function for MR1 in the development of IgA producing plasma cells. Histol Histopathol 24, 1439-1449 (2009)
Key words: Human, MHC, MR1, Mucosa, Plasma cells, IgA
DOI: 10.14670/HH-24.1439