KINETICS OF CYTOKINE GENE-EXPRESSION IN MACROPHAGE AND ENDOTHELIAL-CELL LINES FOLLOWING LIPOSOME-ENCAPSULATED HEMOGLOBIN (LEH) TREATMENT IN-VITRO

Liposome encapsulated haemoglobin (LEH), a blood substitute, has been shown to increase serum IL-6 levels in mice, but the cellular source o f this cytokine is unknown, These experiments were conducted to determ ine cytokine gene expression by macrophages (P388D1) and endothelial c ells (EOMA) after LEH treatment in vitro, P388D1 and EOMA cells were i ncubated with LEH, final concentration of 10%, for 0, 0.5, 1, 2, 4, 8 and 24 h, Total RNA was extracted at the above times and semi-quantita tive RT-PCR was carried out to detect cytokine mRNA expression in the presence of competitive internal standards specific for mouse IL-1 bet a, IL-6, TGF-beta, TNF-alpha. and GM-CSF. The results demonstrated tha t although constitutive cytokine gene expression exists in both cell l ines, the level of IL-6 mRNA was prominently elevated by incubation wi th LEH, rapidly reaching a peak at about 4 h and gradually declining o ver the next 20 h after LEH treatment, In contrast, there was no signi ficant change in mRNA accumulation of IL-1 beta, TGF-beta, TNF-alpha o r GM-CSF at all times, These in vitro findings suggest that macrophage s and endothelial cells may be the cellular sources of the elevated le vels of IL-6 found in serum after in vivo LEH administration. (C) 1996 Academic Press Limited