Identification and functional analysis of Ly-6A/E as a thymic and bone marrow stromal antigen.
We recently described an mAb (MTS23) reactive with a membrane Ag expressed on a subset of thymic medullary stromal cells. This Ag is also constitutively expressed at high levels on peripheral B cells, macrophages, and thymic and splenic dendritic cells of C57BL/6 mice. A number of stromal cell lines derived from thymus and bone marrow also stain with MTS23, but thymocytes and peripheral T cells only weakly express the Ag detected by MTS23. Here we show that the molecule detected by MTS23 is a member of the Ly-6 family of phosphatidylinositol-anchored membrane proteins. Treatment of stromal cells with phosphatidylinositol-phospholipase C before staining completely abolished expression. Using transient expression of 293T cells and a cDNA library of a stromal cell line cloned into the pEF-BOS vector, a cDNA encoding the MTS23-target Ag was isolated. Partial sequencing and restriction enzyme mapping revealed that it represents the Ly-6A/E protein. While the physiologic significance of the presence of Ly-6 molecules on stromal cells is not clear, it has been known for some time that, at least in lymphocytes, cellular activation events can be induced upon Ly-6 engagement. We now demonstrate that Ly-6 also functions as a signal transduction molecule on stromal cells, in that granulocyte-macrophage CSF can be produced by a variety of stromal cell lines upon mAb-mediated cross-linking of Ly-6. Together with the dramatic up-regulation of Ly-6 expression on stromal cells upon IFN-gamma treatment, this is the first indication of a biologic function of an Ly-6 gene product on nonhemopoietic cells. The results suggest that Ly-6 may play a role in the cross-talk between lymphocyte precursors and stromal cells.
Izon
D J
DJ
Division of Immunology, The Netherlands Cancer Insitute, Antoni van Leeuwenhoek Huis, The Netherlands.
Oritani
K
K
Hamel
M
M
Calvo
C R
CR
Boyd
R L
RL
Kincade
P W
PW
Kruisbeek
A M
AM
D000818:Animals; D000911:Antibodies, Monoclonal; D000950:Antigens, Ly / Q000235:genetics / Q000378:metabolism*; D001853:Bone Marrow / Q000276:immunology* / Q000378:metabolism; D001854:Bone Marrow Cells; D002460:Cell Line; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D015398:Signal Transduction / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D003432:Cross-Linking Reagents; D018076:DNA, Complementary; D016178:Granulocyte-Macrophage Colony-Stimulating Factor