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oai:uvadoc.uva.es:10324/101522022-06-28T07:30:28Zcom_10324_1133com_10324_931com_10324_894col_10324_1209

00925njm 22002777a 4500 dc Martín, Margarita author Romero, Xavier author Fuente García, Miguel Ángel de la author Tovar, Victoria author Zapater, Nuria author Esplugues, Enric author Pizcueta, Pilar author Bosch, Jaime author Engel, Pablo author 2001 CD84 is a member of the CD2 subset of the Ig superfamily of cell surface molecules. Its cytoplasmic tail binds to Src homology 2 domain-containing protein 1A (signaling lymphocytic activation molecule-associated protein), a protein encoded by the X-linked lymphoproliferative disease gene. It is preferentially expressed on B lymphocytes, monocytes, and platelets. We show that it is also expressed on thymocytes and T cells. CD84 was positive on CD4 CD8 thymocytes, and its expression decreased with cell maturation. It is expressed on mature T cells preferentially on CD45RO . To identify the CD84 ligand, we generated a soluble Ig fusion protein containing the human CD84 extracellular domains (CD84-Ig). Because receptor-ligand interactions occur between several members of this subfamily, we assayed CD84-Ig binding with all members of the CD2 family. CD84-Ig bound to CD84-transfected cells, whereas no binding was detected with cells expressing other CD2 subfamily receptors, showing that CD84 binds to itself. Anti-CD84 mAbs recognizing epitopes wholly within domain 1 of CD84 blocked the binding of the CD84-Ig fusion protein to CD84-transfected cells and platelets. Data from CD84 domain human/mouse chimeras further revealed that only the first extracellular domain of the molecule is involved in the ligand receptor recognition. The CD84-CD84 interaction was independent of its cytoplasmic tail. Finally, concurrent ligation of human CD84 with mAbs or CD84-Ig and CD3 enhanced IFN-secretion in human lymphocytes. Thus, CD84 is its own ligand and acts as a costimulatory molecule. The Journal of Immunology 2001, 167(7): 3668–3676. 0022-1767 http://uvadoc.uva.es/handle/10324/10152 10.4049/jimmunol.167.7.3668 3668 7 3676 The Journal of Immunology 167 Biología molecular CD84 Functions as a homophilic adhesion molecule and enhances IFN- g secretion:adhesion is mediated by Ig-like domain 1