The Journal of Immunology, Vol 144, Issue 3 804-810, Copyright © 1990 by American Association of Immunologists

ARTICLES

Identification of a new cell surface glycoprotein with accessory function in murine T cell responses

WT Golde, M McDuffie, J Kappler and P Marrack
Department of Chemistry, University of Colorado, Boulder 80309.

T cell binding to target cells involves not only the TCR and its MHC- bound ligand, but also a collection of additional proteins on both the T cell and its target. In an attempt to identify new molecules involved in this binding, mAb were raised against APC, and screened for their abilities to inhibit T cell recognition of Ag plus MHC on B cells. Six antibodies were identified that inhibited this reaction and that bound a cell-surface glycoprotein (Lgp55), with core polypeptide Mr 30,000 and a glycosylated Mr of approximately 55,000 depending upon the cell source. The properties of Lgp55 were consistent with it being the mouse homologue of a recently identified human ligand (intercellular adhesion molecule-2) for lymphocyte functional Ag-1 because the proteins are of comparable Mr, and antibody to Lgp55, like anti-lymphocyte functional antigen-1, blocks T cell recognition of Ag presented by B cells, but not of Ag presented by mouse fibroblasts.