The in vitro activity of lectin I from mistletoe (ML I) and its isolated A and B chains on functions of macrophages and polymorphonuclear cells.
We investigated the effects of ML I and its isolated chains, A and B, in regard to selected functions of phagocytes (human granulocytes, paraffin-oil stimulated M phi from guinea pigs). On these cells, ML I has no cytotoxic effect between 10(-14) and 10(-8) (trypan blue exclusion and ethidium bromide exclusion). Over the same concentration range, ML I and B chain diminish the negative surface charge of M phi and agglutinate M phi at concentrations greater than or equal to 2 X 10(-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 two peaks, indicating the existence of two types of receptors on the M phi surface with different affinities for sugar-binding sites. Moreover, the B chain shows a third peak at higher concentrations (3 X 10(-8) M) that could be inhibited by D-galactose (greater than or equal to 10(-4) M). In comparison, the A chain reduces the surface charge at concentrations over 3 X 10(-7) M, but D-galactose has no effect on this. By means of the agarose droplet test, the spontaneous migration of M phi is inhibited in the sequence ML I much greater than B chain greater than A chain. The phagocytic activity of human leukocytes tested with a radiometric phagocytosis technique reveals an increasing effect only for the B chain; ML I and the A chain have no effect. Perhaps the mechanism of the described activities of ML I and its B chain are comparable with the action of lymphokines activating M phi.
D000818:Animals; D002449:Cell Aggregation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004586:Electrophoresis; D005690:Galactose / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D037102:Lectins / Q000494:pharmacology*; D046911:Macromolecular Substances; D008264:Macrophages / Q000276:immunology*; D014784:Mistletoe; D009504:Neutrophils / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects; D037121:Plant Lectins; D010946:Plants, Medicinal; D012685:Sepharose; D013499:Surface Properties
D037102:Lectins; D046911:Macromolecular Substances; D037121:Plant Lectins; D012685:Sepharose; D005690:Galactose