Indoleamine 2,3-dioxygenase and inducible nitric oxide synthase mediate immune tolerance induced by CTLA4Ig and anti-CD154 hematopoietic stem cell transplantation in a sensitized mouse model.

Cytotoxic T-lymphocyte-associated protein 4 immunoglobulin (CTLA4Ig) and anti-cluster of differentiation 154 (anti-CD154) are able to block B7/CD28 and CD40/CD154 co-stimulatory signals in T cells. Additionally, they promote hematopoietic stem cell transplantation (HSCT) in sensitized recipients and are able to induce immune tolerance and complete hematopoietic reconstitution. Indoleamine 2, 3-dioxygenase (IDO) and nitric oxide (NO) have been implicated in T cell immune tolerance. The aim of the present report was to study the