Non-mannose-capped lipoarabinomannan stimulates human peripheral monocytes to expression of the "early immediate genes" tissue factor and tumor necrosis factor-alpha.

In the present study, we have shown that stimulation of cryopreserved, human peripheral blood monocytes with the cell wall components from Gram-negative bacteria, lipopolysaccharide (LPS), and from rapid-growing Mycobacterium sp., non-mannose-capped lipoarabinomannan (AraLAM), both induce expression of the "early immediate genes" tissue factor (TF) and tumor necrosis factor-alpha (TNF-alpha). This was demonstrated both at the protein and the mRNA levels. Antibodies against the CD14 receptor could block the stimulating effects. AraLAM was a significantly weaker inducer than LPS, and we speculate that this may reside in the number of the fatty acids in the part of the molecule that interacts with the CD14/Toll-like receptors (TLR). Finally, both LPS and AraLAM activated the "early immediate genes" through translocation of the transcription factor proteins NF-kappaB/Rel and increasing the binding activity of AP-1.