Fig. 9. Inhibition of cell proliferation by anti-CD103 antibodies. (A) Isolated CD8⁺ SP thymocytes were co-cultured with primary thymic epithelial cells (Ep/CD8+), which induces a net increase in cell proliferation after 48 hours of culture. Antibodies against HLA-A,B,C (Ep/CD8+/HL) used as control antibodies did not significantly interfere with the proliferation process, whereas antibodies against E-cadherin (Ep/CD8+/a.E-cad) slightly blocked cell proliferation. Anti-CD103 antibodies (Ep/CD8+/a.CD103), however, drastically reduced cell proliferation. Results represent the mean of triplicate experiments. (B) CD103^- CD8⁺ SP thymocytes, when co-cultured with primary thymic epithelial cells for 48 hours, did not show a net increase in cell proliferation (Ep/CD8+/CD103-) whereas CD8⁺-SP-containing CD103⁺ CD8⁺ SP thymocytes did (Ep/CD8+). Antibodies against CD103 inhibited cell proliferation drastically (Ep/CD8+/a.CD103).