Ligand binding to the LFA-3 cell adhesion molecule induces IL-1 production by human thymic epithelial cells.
We have shown that human thymic epithelial (TE) cells produce IL-1 alpha, IL-1 beta, and TE cells bind to thymocytes by CD2 and LFA-1 molecules on thymocytes and LFA-3, ICAM-1 on TE cells. We investigated whether ligand binding to LFA-3 on human TE cells can modulate TE cell IL-1 production. First, we investigated the ability of human thymocytes to regulate IL-1 release by TE cells. Both autologous and allogenic emetine-treated thymocytes when cultured with TE cells augmented IL-1 release by TE cells. The augmentation of IL-1 release was cell density dependent. Inasmuch as the interaction between thymocytes and TE cells is mediated in part by CD2 molecules on thymocytes and LFA-3 molecules on TE cells we next determined the effect on IL-1 release of ligand binding (anti-LFA-3 mAb TS2/9) to TE cell surface LFA-3. Purified anti-LFA-3 mAb augmented IL-1 release in a concentration-dependent fashion. The anti-LFA-3-mediated augmentation of IL-1 release required both new protein and RNA synthesis as shown by the ability of cycloheximide and actinomycin-D to inhibit augmentation of IL-1 production by TE cells, and by direct quantitation of IL-1 alpha and IL-1 beta mRNA by Northern blot analysis. Both F(ab)'2 and Fab' fragments of anti-LFA-3 mAb augmented IL-1 alpha and IL-1 beta mRNA production, indicating that monovalent binding to cell surface LFA-3 was sufficient to provide the inducing signal. The identification of LFA-3, the cell surface ligand for thymocyte CD2 molecules, as a molecule via which TE cell-derived cytokine production may be regulated suggests a mechanism at the cell surface by which direct TE cell-thymocyte interaction might result in the triggering of local IL-1 release within the human thymic microenvironment.
Department of Medicine, Duke University Medical Center, Durham, NC 27710.
P T
PT
Le
L W
LW
Vollger
B F
BF
Haynes
K H
KH
Singer
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D000954:Antigens, Surface / Q000502:physiology*; D015152:Blotting, Northern; D018801:CD2 Antigens; D018968:CD58 Antigens; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics; D008024:Ligands; D008562:Membrane Glycoproteins / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic / Q000502:physiology; D013950:Thymus Gland / Q000502:physiology*
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018801:CD2 Antigens; D018968:CD58 Antigens; D015815:Cell Adhesion Molecules; D007375:Interleukin-1; D008024:Ligands; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D003609:Dactinomycin; D003513:Cycloheximide