Figure 4.

Regulation of T-cell proliferation is reversible and is partially mediated by nitric oxide (NO). Wild-type (WT) or tumour necrosis factor receptor 1 deficient (TNFR1^−/−) bone-marrow-derived macrophages (BM-Mϕ) were co-cultured with OT-II T cells in the presence of 100 μg/ml ovalbumin (OVA) peptide for 72 hr. To some cultures, 300 μmN(G)-mono-methyl-l-arginine (l-NMMA), an arginine analogue, or 30 μmS-nitroso-N-acetyl-l,l-penicillamine (SNAP), a nitric oxide (NO) donor, was added. Plots show the effect of addition of l-NMMA or SNAP on NO production (a) and proliferation (b) on co-cultures containing WT (black bars) or TNFR1^−/− (grey bars) Mϕ, as compared with control untreated co-cultures. These data are representative of four independent experiments. *P < 0·01; †not significantly different.