Mechanism of binding of multivalent immune complexes to Fc receptors. 2. Kinetics of binding

Abstract

The kinetics of association and dissociation of affinity cross-linked IgG oligomers with Fc receptors on P388D1 cells have been studied at 0 degrees C. For dimers prepared with two different affinity cross-linking reagents (DIBADL and BDPE) and also trimers and a heavy oligomer fraction prepared with BDPE, monomeric IgG accelerates the rate of dissociation of bound oligomer from the cells. This observation is consistent with a binding mechanism in which monovalently, and multivalently bound species are in rapid equilibrium with one another on the cell surface and in which the rate of formation of the divalently bound species is faster than the dissociation of the monovalent species from the cells. As predicted, the rates of dissociation of BDPE cross-linked oligomers decrease with size, and dimers (cross-linked with DIBADL) which can self-aggregate on the cell surface dissociate more slowly than nonaggregating (BDPE) dimers. The association and dissociation of oligomers with P388D1 cells proceed by parallel fast and slow processes, even with cells that bind dimers with a single affinity. The origin of this heterogeneity is not known but could arise from a fraction of receptors in environments with limited accessibility to bulk solution. The fast component of the association reaction is second order, and the rate-limiting step of this process is the formation of the monovalently bound intermediate from solution-phase oligomer.

The type 1 receptor (CD120a) is the high-affinity receptor for soluble tumor necrosis factor

“…2 A). Within this plot, the intercept on the ordinate represents the dissociation rate constant and the slope is equal to the association rate constant (27). The resulting mean values from three independent experiments were 0.039 Ϯ 0.012 min for the association rate constant and are thus in good agreement with the values obtained in the experiments described above (Fig.…”

Characterization of the high-affinity cell-surface receptor for murine B-cell-stimulating factor 1.

“…The data show that the final equilibrium amount bound to cells and the rate of approach to equilibrium are dependent on the initial concentration of 1251-BSF-1 in the medium. The curves passing through the data are best-fit single exponential time-dependency curves (26), consistent with the presence of a single population of receptors on these cells. The Inset (Fig.…”

Impact of Benzene Metabolites on Differentiation of Bone Marrow Progenitor Cells

“…Colonies (14). Binding assays were carried out using a phthalate oil separation method (15) as performed by Park et al (14), and association/dissociation kinetics were analyzed as previously described (16,17). Specific activity of each preparation was determined by selfdisplacement analysis (18 (19).…”

“…Normal hematopoiesis is probably the ultimate example of a tightly regulated process in which cell survival, differentiation, and proliferation are inextricably linked and controlled by multiple This paper was presented at Benzene '95: An International Conference on the Toxicity, Carcinogenesis, and Epidemiology of Benzene held [17][18][19][20] June 1995 in Piscataway, New Jersey. Manuscript received 16 January 1996; manuscript accepted 14 June 1996. growth factors or cytokines that collaborate to regulate hematopoiesis (3).…”