Characterization of C1 inhibitor binding to neutrophils

Nan-Shan Chang, R. J. Boackle, R. W. Leu

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

In a previous study we have isolated neutrophil membrane proteins that non-covalently bind to native C1-INH (105,000 MW) and a non-functional, degraded C1-INH (88,000 MW; C1-INH-88). To further characterize the binding nature, we have designed a novel kinetic C1 titration assay which enables not only a quantification of the removal of fluid-phase C1-INH by neutrophils, but also a concomitant measure of residual C1-INH function. Native C1-INH, when adsorbed to EDTA-pretreated neutrophils, lost its function in the inhibition of fluid-phase C1. The non-functional C1-INH-88, which is probably devoid of a reactive centre, was found to block the binding of native C1-INH to neutrophils. Pretreatment of neutrophils with serine esterase inhibitors did not abrogate binding capacity of the cells for C1-INH, whereas the binding affinity for C1-INH was lost when the cells were pretreated with trypsin. An array of human peripheral blood leucocytes and several lymphoid cell lines has surface binding sites for C1-INH, but not on human erythrocytes and U937 cells. Binding was further confirmed using (i) C1-INH-microsphere beads to neutrophils, in which the binding was blocked when pretreating neutrophils with excess C1-INH or with trypsin, and (ii) radiolabelled C1-INH to neutrophils, which was competitively blocked by unlabelled non-functional C1-INH-88. Desialylation of C1-INH significantly reduced its binding affinity for neutrophils, indicating that the membrane receptor sites on neutrophils could be specific for the binding of sialic acid residues on C1-INH. Overall, our studies indicate that neutrophils or other leucocytes possess specific surface binding sites for the sialic acid-containing portion of C1-INH.

Original languageEnglish
Pages (from-to)95-101
Number of pages7
JournalImmunology
Volume73
Issue number1
Publication statusPublished - 1991 Jan 1

Fingerprint

Neutrophils
N-Acetylneuraminic Acid
Trypsin
Leukocytes
Binding Sites
U937 Cells
Microspheres
Edetic Acid
Membrane Proteins
Erythrocytes
Lymphocytes
Cell Line
Membranes

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

Cite this

Chang, N-S., Boackle, R. J., & Leu, R. W. (1991). Characterization of C1 inhibitor binding to neutrophils. Immunology, 73(1), 95-101.
Chang, Nan-Shan ; Boackle, R. J. ; Leu, R. W. / Characterization of C1 inhibitor binding to neutrophils. In: Immunology. 1991 ; Vol. 73, No. 1. pp. 95-101.
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Chang, N-S, Boackle, RJ & Leu, RW 1991, 'Characterization of C1 inhibitor binding to neutrophils', Immunology, vol. 73, no. 1, pp. 95-101.

Characterization of C1 inhibitor binding to neutrophils. / Chang, Nan-Shan; Boackle, R. J.; Leu, R. W.

In: Immunology, Vol. 73, No. 1, 01.01.1991, p. 95-101.

Research output: Contribution to journalArticle

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Chang N-S, Boackle RJ, Leu RW. Characterization of C1 inhibitor binding to neutrophils. Immunology. 1991 Jan 1;73(1):95-101.