Specific inhibition of mRNA accumulation for lymphokines in human T cell line Jurkat by mycobacterial lipoarabinomannan antigen

Abstract

SUMMARY The immunomodulatory effect of Mycobucterium tuberculosis-derived lipoarabinomannan (LAM) on mitogen/antigen-induced expression of mRNAs for a number of cytokines in human monocytic cell line Mono-Mac-6 and in T cell line Jurkat was investigated. Interestingly, LAM exhibited a down-regulatory effect on the accumulation of mRNAs for IL-2, IL-3, granulocyle-macrophage colony-stimulating factor (GM-CSF), and IL-2 receptor alpha (IL-2Rα) in T cells co-stimulated with phytohaemagglutinin-P (PHA) and 4β-phorbol-12-myristyl-13-acetate (PMA). In human Mono-Mac-6 cells, LAM has a weak inhibitory effect on the lipopolysaccharide (LPS)-induced mRNA accumulation for IL-1β, a slight stimulatory effect on mRNAs accumulation for IL-8 and tumour necrosis factor-alpha (TNF-α). but clearly no effect on mRNA accumulation for intercellular adhesion molecule-1 (ICAM-I). These findings imply that LAM may contribute to the immunologic defects associated with a number of mycobacterial infections by modulating these mediators.