CD2 is a surface antigen of the human T-lymphocyte lineage that is expressed on all peripheral blood T cells (summarized by Sewell et al., 1986 [PubMed 3490670]). It is one of the earliest T-cell markers, being present on more than 95% of thymocytes, it is also found on some natural killer cells but not on B lymphocytes. Monoclonal antibodies directed against CD2 inhibit the formation of rosettes with sheep erythrocytes, indicating that CD2 is the erythrocyte receptor or is closely associated with it.
