Humanized Anti- CD6 Monoclonal Antibody Injection (T1h mab or T1AhT mab) The CD6 molecule is a membrane associated glycoprotein expressed mainly on T cells and by a small population of B cells. The expression of the natural ligands of this surface marker has been described on activated T cells, B cells, monocytes, dermal fibroblasts and synovial cells. The CD6 interaction with its ligands is correlated with crucial cellular events, such as cells adhesion, maturation, activation and survival. The above information justify why this lymphocyte marker is actually emerging as a potential target for therapeutic intervention in autoimmune diseases. T1h is a humanized anti-CD6 monoclonal antibody obtained according GMP resulted less immunogenic than its murine precursor in monkeys (Cercopithecus aethiops) and with a superior half life in rabbits.T1h inhibit the CD6 function of stimulating T cell activation through specificity combination with CD6 on the surface of immune cells to prevent autoimmune system to attack target tissue, which achieve the purpose of treatment autoimmune diseases such as rheumatoid arthritis (RA). Preclinical research results have demonstrated that the pharmacological mechanism of T1h is that T1h recognizes the membrane-distal domain (SRCR1) of CD6, then form immune complex (T1h-SRCR1) through the internalization mechanism into cells, reduce the CD6 level of lymphocyte surface to hinder the immune synapse form by CD6 molecules with TCR/CD3, which decreased phosphorylation levels of STAT3, MAPK, AKT signaling pathway were, inhibited lymphocyte activation and proliferation, and significantly reduced the expression and secretion of inflammatory cytokine, such as IFN-γ, IL-6 and TNF-α. T1h was approved for clinical research to treat psoriasis and RA in Cuba and India. Phase I clinical research in Cuba recruited 13 patients, completed in 2007. Pase I clinical research in India completed 70 patients with RA and 40 patients with psoriasis in 2007 and started phase II clinical research on psoriasis in 2008. So far, more than 100 patients entered the clinical trials of autoimmune disease via T1h treatment. The treatment efficacy and safety of T1h have been evaluated. Now, phase III clinical trials of T1h against psoriasis, rheumatoid arthritis are underway. The moderately severe psoriatic patients displayed good tolerance to T1h treatment and no severe adverse reactions, which proves T1h has high safety to prove the patients’ life quality.