Endotoxin contamination in commercially available pokeweed mitogen contributes to the activation of murine macrophages and human dendritic cell maturation.
Commercially available pokeweed mitogen (PWM) has been reported to activate macrophages, leading to production of proinflammatory cytokines and nitric oxide (NO). However, we found that polymyxin B (PMB), a specific inhibitor of endotoxin activity, inhibited the PWM-induced expression of proinflammatory cytokines and NO and the activation of Toll-like receptor 4 (TLR4). A kinetic-turbidimetric Limulus amebocyte lysate assay demonstrated that commercial PWM contained substantial endotoxin, over 10(4) endotoxin units/mg of the PWM. A PWM repurified by PMB-coupled beads no longer induced the expression of proinflammatory cytokines, TLR4 activation, or dendritic cell maturation. However, the repurified PWM remained able to induce proliferation of human lymphocytes, which is a representative characteristic of PWM. These results suggest that commercial PWM might be contaminated with a large amount of endotoxin, resulting in the attribution of misleading immunological properties to PWM.
Yang
Jae Seung
JS
International Vaccine Institute, SNU Research Park, San 4-8 Bongcheon-7 dong, Kwanak-gu, Seoul 151-818, Republic of Korea.
Kim
Hye Jin
HJ
Ryu
Young Hee
YH
Yun
Cheol-Heui
CH
Chung
Dae Kyun
DK
Han
Seung Hyun
SH
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D004306:Dose-Response Relationship, Immunologic; D004340:Drug Contamination; D004731:Endotoxins / Q000009:adverse effects*; D006801:Humans; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D029604:Phytolacca americana; D011043:Pokeweed Mitogens / Q000494:pharmacology*
D004731:Endotoxins; D011043:Pokeweed Mitogens