NMMA inhibits NO production and cytostatic activity mediated by acute GVHD-primed, LPS-triggered Mφ.

Acute GVHD Mφ (▪) from B6AF₁ animals transplanted 14 days previously with 60 × 10⁶ B6 cells were activated with 2.5 ng/mL LPS, and normal Mφ (■) from B6AF₁animals were activated with 2.5 ng/mL LPS and IFN-γ. (A) The concentration of NO in 48-hour culture supernatants was determined as described in “Materials and methods.” Mφ were cultured in phenol red–free RPMI 1640 containing 1.0 mmol/L L-arginine plus 10% FCS with or without NMMA as indicated. Results represent the mean ± SD of triplicates. Similar results were obtained in 2 separate experiments. (B) Mφ-mediated cytostasis of MDW4 cells was determined as described in “Materials and methods.” Mφ and targets were cultured for 48 hours in RPMI 1640 plus 10% FCS containing 1.0 mmol/L L-arginine either with or without NMMA as indicated. Results represent the mean ± SEM of 3 experiments.