Anti-lipoteichoic acid antibodies enhance release of cytokines by monocytes sensitized with lipoteichoic acid

Lipoteichoic acid (LTA) from gram-positive bacteria can stimulate monocytes to produce cytokines. To ascertain whether aggregation of LTA receptors can contribute to this effect, human monocytes were sensitized with LTA from Streptococcus pyogenes, washed, and treated with anti-LTA antibodies. The addition of anti-LTA antibodies or F(ab')₂ fragments markedly enhanced the aggregation of LTA receptors, as evidenced by indirect immunofluorescence and the release of tumor necrosis factor alpha and interleukin-1β. These findings suggest that aggregation of LTA receptors of monocytes is required for triggering marked cytokine responses.