Nitric oxide production and apoptosis by GP120

Nitric oxide (NO) is increased by gp120 in astrocytes and in monocyte-deriv ed macrophages. Of the gp120 fragments (F1:amino acid 254-274, F2: amino ac id 315-329 F3: amino acid 421-438), FI has been shown to increase NO in ast rocytes and gp120 also primes CD4(+) T cells for apoptosis. Peripheral bloo d mononuclear cells (PBMCs) at 10(6)/ml (N = 10) were incubated at 24 and 7 2 hours in RPMI, 10% CO2 with low closes (100 nM) gp120 and high doses (400 NM) of the smaller fragments. Supernatants were collected and assayed for the relative contribution of gp120 and its fragments on NO production at bo th time points. Apoptosis was detected by in situ hybridization with and wi thout I mu g/ml LPS as superantigen at 72 hours. The major contribution to apoptosis and NO production was from FI. Ar 24 hours FI had a 1.9-fold incr ease from control, whereas F2 and F3 had 1.25- and 1.35,fold increases. At 72 hours both FI and F2 had a 1.5-fold increase and F3 had a 1.33 increase. Thus, FI contributed significantly to NO production at 24 hours. Both Fl a nd F2 had significant contributions to NO production at 72 hours. FI had th e most contribution to apoptosis both with and without lipopolysaccharide ( LPS). These findings may contribute to further understanding the mechanism HIV-induced apoptosis.