CD58, or lymphocyte function-associated antigen 3 (LFA-3), is a cell adhesion molecule expressed on Antigen Presenting Cells (APC), particularly macrophages. It binds to CD2 (LFA-2) on T cells and is important in strengthening the adhesion between the T cells and Professional Antigen Presenting Cells. This adhesion occurs as part of the transitory initial encounters between T cells and Antigen Presenting Cells before T cell activation, when T cells are roaming the lymph nodes looking at the surface of APCs for peptide:MHC complexes the T-cell receptors are reactive to.