The Inhibitory Effects of Mycobacterial Lipoarabinomannan and Polysaccharides Upon Polyclonal and Monoclonal Human T Cell Proliferation

Lipoarabinomannan from Mycobacterium tuberculosis was able to inhibit antigen induced T cell proliferation of human CD4+ T cell clones specific for influenza virus. The inhibitory effect was also present when peripheral human T cells were stimulated with crude mycobacterial antigen extracts. Non-specific T cell stimulation, i.e. IL-2, PHA and anti-CD3 antibodies coupled to beads, was not affected. The inhibitory property was also found when arabinomannan and arabinogalactan of mycobacterial origin were tested but not with other unrelated polysaccharides used as controls. The effect appears to be related to the processing of the antigen by the antigen-presenting cells, since it was evident when T cell clones were stimulated with whole virus, whereas stimulation with a synthetic peptide containing the relevant epitope was not inhibitable.