Synthesis of a thymosin beta 4-like peptide, thymosin beta Met9, and its effect on low E-rosette-forming lymphocytes of lupus nephritis patients.

A thymosin beta 4-like peptide, thymosin beta Met9 isolated from pork spleen, was synthesized using a conventional solution method. The deprotection of the protected thymosin beta Met9 was achieved by treatment with Zn-90% AcOH to remove C-terminal p-nitrobenzyl ester and then with 1 M trifluoromethanesulfonic acid-thioanisole (molar ratio, 1:1) in trifluoroacetic acid in the presence of dimethylselenium. Finally, the deprotected peptide was incubated with dithiothreitol to reduce sulfoxide on the methionine side chain. The increase of the E-rosette-forming lymphocytes was obtained after incubation of peripheral blood from lupus nephritis patients with the synthetic thymosin beta Met9. The synthetic thymosin beta Met9 was approximately equal in potency to that of our synthetic calf thymosin beta 9.