In vitro activation of macrophages by a novel proteoglycan isolated from corms of Crocus sativus L

Saffron corms contain a proteoglycan that is highly cytotoxic on human tumo r cells. The present work was undertaken to study the possible immunomodula tory and anti-invasive properties of this compound. Non-cytotoxic concentra tions of this glycoconjugate promoted significant macrophage activation, de tected by the release of nitric oxide. A rapid activation of protein kinase C and NF-kappa B was obtained after proteoglycan treatment, which could ex plain the induction of nitric oxide synthase. Proteoglycan concentrations r anging from 10-1000 ng/ml specifically promoted apoptosis of macrophages, p robably triggered by their activation. This molecule did not inhibit in vit ro migration or invasion of human tumor cells. Altogether these results sup port a plausible immune-modulating activity for this saffron Crocus compoun d. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.