Good or evil: CD26 and HIV infection

Acquired immune deficiency syndrome (AIDS:) is an incurable disease at pres ent and so many efforts to conquer this disease are being made around the w orld. In studies of human immunodeficiency virus (HIV) infection and the di sease progression. it has been reported that T cells expressing CD26 are pr eferentially infected and depleted in HIV-infected individuals. CD26 is a w idely distributed 110 kDa cell-surface glycoprotein with known dipeptidyl p eptidase IV (DPPIV) activity in its extracellular domain. This ectoenzyme i s capable of cleaving N-terminal dipeptides from polypeptides with either p roline or alanine residues in the penultimate position. On human T cells. C D26 exhibits the co-stimulatory function and plays an important role in imm une response via its ability to bind adenosine deaminase (ADA) and associat ion with CD45. Recent studies have been stripping the veil from over the re lationship between CD26 and HIV infection. Susceptibility of cells to HIV i nfection is correlated with CD26 expression. and HIV transactivator Tat and envelope protein gp120 are reported to interact with CD26. These observati ons indicate that CD26 is closely involved in HIV cell entry and that CD26- mediatod T cell immune response is suppressed. In addition. it has been dem onstrated that the anti-HIV and chemotactic activities of RANTES (regulated on activation. normal T cell expressed and secreted) and stromal cell-deri ved factor-1 (SDF-1) are controlled with the DPPIV activity of CD26. Thus. the regulation of the function of chemokines by CD26/DPPIV appears to be es sential fbr lymphocyte trafficking and infectivity of HIV strains. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.