A natural carbohydrate inhibits LFA-1 and MAC-1 mediated adhesion

Acemannan Immunostimulant (ACM), a derivative of the Aloe vera plant containing >75% of an acetylated mannan, has antiinflammatory effects in vivo. In mouse models, it inhibits neutrophil emigration into skin and lung tissue by >50%. In the current study we assessed the hypothesis that ACM influences the mobility of neutrophils by altering chemotactic responses or cellular adhesive mechanisms. Using isolated human neutrophils, we evaluated chemotactic migration, shape change, upregulation of CD lib/CD 18 and shedding of L-selectin in response to fMLP and IL-8, and found no inhibitory activity of ACM over a wide concentration range. ACM had no effect on neutrophil adhesion to P- or E-selectin transfected target cells measured under static conditions. Mac-1-dependent neutrophil adhesion was assessed using protein-coated glass as a substrate. Peak inhibition of adhesion was seen at 30 //g/ml of ACM (45% inhibition, p=0.02, n=9). LFA-1-dependent adhesion to ICAM-1-transfected L cells was maximally inhibited by 10 /jg/ml ACM (36% inhibition, p=0.03, n=8). These effects on adhesion remained after removing free ACM. ACM had no effects on ligands used in these studies and did not activate human neutrophils. It appears from these results that the antiinflammatory effect of ACM may involve inhibition of adhesive function of at least two members of the CD18 integrins.

A natural carbohydrate inhibits LFA-1 and MAC-1 mediated adhesion Academic Article