ARTIFICIAL CELL-SURFACE CONSTRUCTS FOR STUDYING RECEPTOR-LIGAND CONTRIBUTIONS TO LYMPHOCYTE-ACTIVATION

T-cell activation involves interactions between a number of different receptors on the T-cell with their respective ligands on the antigen p resenting cell. One approach to studying the contributions of the indi vidual receptors is the use of purified Ligands, alone or in combinati on, to stimulate the cells. However, effective T-cell recognition requ ires that the ligands be displayed on a surface having dimensions simi lar to those of a cell. Methods are described for the rapid and effici ent immobilization of purified membrane proteins, including class I MH C proteins, B7.1 and ICAM-1, on 5 mu m diameter latex microspheres in a manner that preserves biological activity. Non-membrane proteins, su ch as anti-receptor antibodies, can be immobilized in a similar manner and can be coimmobilized along with membrane proteins. These artifici al cell surface constructs can be handled in the same way as cells, in cluding characterization by flow cytometry using antibodies specific f or the immobilized proteins and stimulation of T-cell responses. The d ensity of ligand on the surface of the microspheres can be easily vari ed and controlled and multiple proteins can be immobilized on the same surface. Thus, the described methods provide a great deal of flexibil ity in assessing the contributions of the various receptors to T-cell signaling and activation, and should be applicable to the study of oth er cell-cell interactions. (C) 1997 Elsevier Science B.V.