CHEMICALLY SYNTHESIZED SDF-1-ALPHA ANALOG, N33A, IS A POTENT CHEMOTACTIC AGENT FOR CXCR4 FUSIN/LESTR-EXPRESSING HUMAN-LEUKOCYTES/

Stromal cell-derived factor (SDF) 1 is a potent chemoattractant for le ukocytes through activation of the receptor CXCR4/Fusin/LESTR, which i s a fusion co-factor for the entry of T lymphocytotropic human immunod eficiency virus type 1 (HIV-1), This CXCR4-mediated HIV-1 fusion can b e inhibited by SDF-1, Because of its importance in the study of immuni ty and AIDS, large scale production of SDF-1 is desirable, In addition to recombinant technology, chemical synthesis provides means by which biologically active proteins can be produced not only in large quanti ty but also with a variety of designed modifications, In this study, w e investigated the binding and function of an SDF-1 alpha analogue, N3 3A, synthesized by a newly developed native chemical ligation approach , Radioiodinated N33A showed high affinity binding to human monocytes, T lymphocytes, as well as neutrophils, and competed equally well with native recombinant SDF-1 alpha for binding sites on leukocytes. N33A also showed equally potent chemoattractant activity as native recombin ant SDF-1 alpha for human leukocytes. Further study with CXCR4/Fusin/L ESTR transfected HEK 293 cells showed that N33A binds and induces dire ctional migration of these cells in vitro. These results demonstrate t hat the chemically synthesized SDF-1 alpha analogue, N33A, which can b e produced rapidly in large quantity, possesses the same capacity as n ative SDF-1 alpha to activate CXCR4-expressing cells and will provide a valuable agent for research on the host immune response and AIDS.