IFNγ, TNF and reactive nitrogen intermediates (RNI; measured using nitric oxide synthase (NOS-2) as a surrogate marker) are all critical for the control of L. donovani infection [9]–[11],[17], and mRNA encoding all of these molecules was significantly reduced (p<0.05) in the livers of mice receiving anti-VCAM-1 mAb (Figure 1D–F) at day 14 p.i. To confirm that VLA-4 was the main integrin interacting with VCAM-1 during VL, we also blocked this molecule using antibody over the first 14 days of infection, and obtained very similar results (Figure 2). Here, NOS2 is linked to infection.