The T11(3) epitope of the CD2 molecule, sheep erythrocytes, and the alternative T-cell activation pathway.

In this study, results are presented showing that the T11(3) epitope of the CD2 molecule is expressed on unfractionated peripheral blood mononuclear cells, resting T cells and activated T cells. T11(3) is not therefore, an activation-specific CD2 epitope. Sheep erythrocytes (SRC) which present a cell-surface ligand for CD2 could not effectively replace anti-T11(2) in initiating proliferation of resting T cells, stimulated by anti-T11(3). SRC with either of these anti-CD2 monoclonal antibodies did activate resting T cells, but proliferation required the presence of added IL-2.