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Characterization of complement receptor type 4 (CR4), a receptor on neutrophils and platelets for C3dg

Thesis/Dissertation ·
OSTI ID:5347265
C3dg, the final in vivo cleavage product of the third component of complement, was purified to homogeneity and its binding to neutrophils from various donors was assessed. It bound with an apparent K/sub a/ of 2 x 10/sup 7/ M/sup -1/, with a range of 2000 to 20,000 molecules bound per cell at saturation (n = 9). The specificity of this receptor for other fragments of C3 was investigated. Neutrophils were incubated with /sup 125/I-C3dg and varying amounts of unlabeled C3b, iC3b, C3dg or C3b and the inhibition of radiolabeled ligand binding was determined. C3b was unable to inhibit binding of /sup 125/I-C3dg to neutrophils, but iC3b, C3dg and C3d inhibited binding equally well. The relationship of this receptor to other complement receptors was investigated using antibodies directed against these receptors. Other peripheral blood cells were investigated for binding to C3dg. Cells were analyzed by indirect fluorescent flow cytometry. The binding characteristics of C3dg to platelets were determined using radiolabeled ligand
Research Organization:
Harvard Univ., Cambridge, MA (USA)
OSTI ID:
5347265
Country of Publication:
United States
Language:
English