Isolation of a yeast heptaglucoside that inhibits monocyte phagocytosis of zymosan particles.
To isolate a unit ligand recognized by human monocyte beta-glucan receptors, acid-solubilized oligoglucosides were prepared by partial acid hydrolysis of purified yeast cell walls, gel filtered sequentially on Bio-Gel P-4 and P-2, derivatized with 2-aminopyridine, and separated by normal-phase HPLC. Ligand recognition was assessed by quantitating the effect of pretreatment with isolated materials on the capacities of adherent monocytes to phagocytose zymosan particles. Partial acid hydrolysis solubilized 23 +/- 4% (mean +/- SD; n = 7) of the cell wall glucans; at an input of 50 micrograms/ml, the solubilized products reduced the numbers of monocytes ingesting zymosan by an average of 44%. Gel filtration of acid-solubilized glucans on Bio-Gel P-4 revealed several peaks with phagocytosis-inhibiting activity, and fractions from the peak containing the smallest oligoglucosides, which accounted for 10 +/- 2% (mean +/- SD; n = 7) of the carbohydrate applied, were pooled. Further purification on Bio-Gel P-2 resolved this phagocytosis-inhibiting activity to a single peak that contained apparent heptaoses and accounted for 8 +/- 2% (mean +/- SD; n = 6) of the carbohydrate applied. At a concentration of 0.5 microgram/ml, the oligoglucosides pooled from the Bio-Gel P-4 and P-2 columns reduced the numbers of ingesting monocytes by 45 +/- 1% and 42 +/- 7% (mean +/- SD; n = 3), respectively. When derivatized with 2-aminopyridine, the oligoglucosides were resolved by HPLC to a number of peaks; a peak that eluted as an apparent heptaglucoside contained virtually all the inhibitory activity and accounted for only 6.6 +/- 0.7% (mean +/- SD, n = 7) of the carbohydrate applied. Gas chromatography analysis revealed only glucose and FAB-mass spectrometric analysis showed only heptaglucoside and no noncarbohydrate molecules. At a concentration of 1.6 ng/ml, the derivatized yeast heptaglucoside reduced the numbers of monocytes ingesting zymosan and glucan particles by 44 +/- 9% (mean +/- SD; n = 5) and 45 +/- 6% (n = 3), respectively. Thus, a heptaglucoside present in yeast cell walls is a unit ligand for human monocyte beta-glucan receptors.
Janusz
M J
MJ
Department of Medicine, Harvard Medical School, Boston, MA.
Austen
K F
KF
Czop
J K
JK
D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005936:Glucans / Q000378:metabolism / Q000494:pharmacology; D005960:Glucosides / Q000302:isolation & purification* / Q000502:physiology; D006027:Glycosides / Q000302:isolation & purification*; D006801:Humans; D006868:Hydrolysis; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D011971:Receptors, Immunologic / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000032:analysis* / Q000276:immunology; D015054:Zymosan / Q000276:immunology*
D005936:Glucans; D005960:Glucosides; D006027:Glycosides; D011971:Receptors, Immunologic; D015054:Zymosan