Evidence for in vitro regulation of IgE receptors on the human basophil membrane by their removal and reexpression: effects of Ca2+, Mg2+, some metabolic inhibitors and fetal calf serum.
Human basophils free of receptor-bound IgE and suspended in RPMI-1640 + 0.2% EDTA or in a buffered salt solution lacking Ca2+ and Mg2+ bound optimal quantities of 125I IgE. In media containing Ca2+ and Mg2+ such as RPMI-1640 alone or a buffered physiologic salt solution binding was reduced significantly in the first 60 min and remained essentially unchanged in the next 120 min. Scatchard analysis showed the reduction to be due both to loss of number and affinity of receptors. The presence of both 2-deoxy-d-glucose and 2,4-dinitrophenol usually prevented the reduction of binding in RPMI-1640. Suspension of cells in RPMI-1640 supplemented with fetal calf serum (FCS) demonstrated reduction in binding at 60 min characteristic of divalent-cation-containing media but this was followed by a rise in binding to approximately control levels in the next 120 min. This pattern of binding occurred in about 70% of the experiments. In most of the remaining experiments there was no difference from control binding in that there was no early decrease and no late rise in binding. This variability was not leukocyte-donor-dependent. When cells were preloaded with 125I IgE and incubated in RPMI-1640 dissociation of IgE was more rapid than in media free of Ca2+ and Mg2+. The results suggest that membrane-bound IgE receptors on basophils may be shed by an energy and Ca2+ and Mg2+ requiring process and reexpressed dependent on a factor or factors present in FCS.
Pruzansky
J J
JJ
Department of Medicine, Northwestern University Medical School, Chicago.
Patterson
R
R
D019297:2,4-Dinitrophenol; D000818:Animals; D001491:Basophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D001790:Blood Physiological Phenomena; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D003470:Culture Media / Q000494:pharmacology; D003837:Deoxy Sugars / Q000494:pharmacology*; D003847:Deoxyglucose / Q000494:pharmacology*; D004140:Dinitrophenols / Q000494:pharmacology*; D004705:Endocytosis; D007073:Immunoglobulin E / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology*; D011961:Receptors, Fc / Q000378:metabolism*; D017455:Receptors, IgE
D003470:Culture Media; D003837:Deoxy Sugars; D004140:Dinitrophenols; D011961:Receptors, Fc; D017455:Receptors, IgE; D007073:Immunoglobulin E; D003847:Deoxyglucose; D008274:Magnesium; D019297:2,4-Dinitrophenol; D002118:Calcium