The in vitro activity of lectin I from mistletoe (MLI) and its isolated A and B chains on functions of macrophages and polymorphonuclear cells
Journal/Book: Immunobiol. 169,461-471. 1985;
Abstract: We investigated the effects of ML I and its isolated chains, A and B, inregard to selected functions of phagocytes (human granulocytes,paraffin-oil stimulated M phi from guinea pigs). On these cells, ML Ihas no cytotoxic effect between 10(-14) and 10(-8) (trypan blueexclusion and ethidium bromide exclusion). Over the same concentrationrange, ML I and B chain diminish the negative surface charge of M phiand agglutinate M phi at concentrations greater than or equal to 2 X10(-8) M (ML I) and greater than or equal to 3 X 10(-7) M (B chain),respectively. The diminishing of the negative surface charge shows twopeaks, indicating the existence of two types of receptors on the M phisurface with different affinities for sugar-binding sites. Moreover, theB chain shows a third peak at higher concentrations (3 X 10(-8) M) thatcould be inhibited by D-galactose (greater than or equal to 10(-4) M).In comparison, the A chain reduces the surface charge at concentrationsover 3 X 10(-7) M, but D-galactose has no effect on this. By means ofthe agarose droplet test, the spontaneous migration of M phi isinhibited in the sequence ML I much greater than B chain greater than Achain. The phagocytic activity of human leukocytes tested with aradiometric phagocytosis technique reveals an increasing effect only forthe B chain; ML I and the A chain have no effect. Perhaps the mechanismof the described activities of ML I and its B chain are comparable withthe action of lymphokines activating M phi. Author.