Temperature effect on IgE binding to CD23 versus Fc epsilon RI.
A chimeric soluble CD23, consisting of the extracellular domain of mouse CD23 and a modified leucine zipper (lz-CD23), has been shown to inhibit IgE binding to the FcepsilonRI. A similar human CD23 construct was also shown to inhibit binding of human IgE to human FcepsilonRI. In both systems, the inhibition was found to be temperature dependent; a 10-fold molar excess of lz-CD23 gave 90-98% inhibition at 4 degrees C, dropping to 20-30% inhibition at 37 degrees C. Surface plasmon resonance analysis of lz-CD23 binding to an IgE-coated sensor chip suggested that the effective concentration of lz-CD23 was lower at the higher temperatures. Analysis of (125)I-IgE binding to CD23(+)-Chinese hamster ovary cells also indicated that increased temperature resulted in a lower percentage of IgE capable of interacting with CD23. In contrast, IgE interacts more effectively with FcepsilonRI(+)-rat basophilic leukemia cells at 37 degrees C compared with 4 degrees C. The results support the concept that the open and closed IgE structures found by crystallography interact differently with the two IgE receptors and suggest that temperature influences the relative percentage of IgE in the respective structural forms. Changes in CD23 oligomerization also plays a role in the decreased binding seen at physiological temperatures.
Chen
Bing-Hung
BH
Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA.
Kilmon
Michelle A
MA
Ma
Check
C
Caven
Timothy H
TH
Chan-Li
Yee
Y
Shelburne
Anne E
AE
Tombes
Robert M
RM
Roush
Eric
E
Conrad
Daniel H
DH
D000818:Animals; D001666:Binding Sites, Antibody / Q000235:genetics; D001667:Binding, Competitive / Q000235:genetics / Q000276:immunology; D016466:CHO Cells; D003080:Cold Temperature; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007073:Immunoglobulin E / Q000378:metabolism*; D016350:Leucine Zippers / Q000235:genetics / Q000276:immunology; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism; D051379:Mice; D051381:Rats; D017455:Receptors, IgE / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D020349:Surface Plasmon Resonance; D013696:Temperature; D014407:Tumor Cells, Cultured; D001619:beta-N-Acetylhexosaminidases / Q000037:antagonists & inhibitors / Q000378:metabolism
D004791:Enzyme Inhibitors; D017455:Receptors, IgE; D011993:Recombinant Fusion Proteins; D007073:Immunoglobulin E; D001619:beta-N-Acetylhexosaminidases