High molecular weight dextran sulfate increases the activity of NF-kappaB-regulated promoter in monocyte-derived macrophages. It is known that sulfated polysaccharides can mimic the action of common T-cell mitogens. To investigate the molecular basis of the mitogenic effect of high molecular weight dextran sulfate (HMDS), monocyte-derived macrophages were transfected with recombinant plasmid containing chloramphenicol acetyl transferase (CAT) reporter gene under the control of the HIV-1 long terminal repeat (LTR) promoter, which is regulated by transcription factor NF-kappaB. We observed that HMDS, similar to bacterial lipopolysaccharide (LPS), increases the expression of CAT reporter gene suggesting increased activity of NF-kappaB. The activation of NF-kappaB correlated with the increased expression of B7.1 molecules. It was postulated that this NF-kappaB-regulated promoter might play a role in the activation of the accessory cells as well as the rate of replication of HIV-1 in monocyte-derived macrophages.