Abstract
Ricin induced the release of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 beta by human peripheral-blood mononuclear cells in a dose- and time-dependent manner. The inhibition induced by ricin upon the phytohaemagglutinin (PHA)-driven lymphocyte proliferation was greater in cultures of mononuclear cells than that observed in monocyte-free cultures of lymphocytes, and was decreased after addition of an anti-TNF-alpha antibody to PHA-activated cultures. Low levels of TNF-alpha were detected in plasma from rats poisoned with ricin. These results suggest that ricin induced the release of macrophage-derived cytokines which may have a role in the pathogenesis of ricin toxic effects.