Immune effector mechanism in parasitic infections

In this article is a summary of our recent findings on the role of nitric o xide (NO) as an effector mechanism against the intracellular parasite, Leis hmania major. NO is produced in large amounts in murine macrophages followi ng activation by IFN gamma synthesized by Th1 cells. NO production is inhib ited by IL-4, a product of Th2 cells. A set of stable cell surface markers has now been identified. ST2L and IL-18R are selectively expressed on Th2 a nd Th1 cells respectively. Antibody against ST2L can down-regulate Th2 cell s in the highly susceptible BALB/c mice leading to control of otherwise fat al L. major infection. These results show directly the critical role of the balance between Th1 and Th2 cells in cutaneous leishmaniasis. (C) 1999 Els evier Science B.V. All rights reserved.