IDENTIFICATION OF CELL-SURFACE RECEPTORS FOR THE ACT-2 CYTOKINE

We have identified cell surface receptors for Act-2, a secreted protein expressed upon activation of T cells, B cells, and monocytes. Although 125I-Act-2 showed little, if any, specific binding to resting peripheral blood lymphocytes (PBL) receptors were readily detected on PHA/PMAactivated PBL and a variety of cell lines including MT2, HL60, DMSO differentiated HL60, HeLa, and K562 cells. The equilibrium dissociation constant (Kd) is 3-12 nM for MT2, K562, and PBL activated with PHA/PMA for 40-80 h. We have also identified a rabbit polyclonal antiserum that can block Act-2 binding to its receptors. The ability to detect specific Act-2 receptors and the development of a blocking antiserum should prove valuable in efforts to molecularly clone the Act-2 receptor and to dissect the biological actions of Act-2. © 1990, Rockefeller University Press., All rights reserved.