| Popis: |
Adsorption of fibrinogen (Fg) appears to be an important precusor of platelet reactivity with artificial surfaces. We have reported that, contrary to the prevailing view, platelet reactivity is less well correlated with the total concentration of adsorbed Fg on the surface than with the concentration of adsorbed Fg detectable by labelled anti-Fg polyclonal antibodies ("native" Fg), and therefore presumably recognizable by the platelet's Fg receptors. To clarify the nature of the conformational change in Fg implied by these findings, we measured Fg adsorbed on a series of polyalkyl methacrylates, using a solid phase RIA in methacrylate-coated microtiter wells with monoclonal antibodies (MoAb) directed against a variety of Fg epitopes. Total Fg adsorption (125I-Fg) was the same on polymethyl methacrylate (PMMA, single carbon side chain) as on polybutyl methacrylate (PBMA, 4 carbon side chain), but platelet reactivity in a bead column was greater on PBMA than on PMMA. Adsorbed "native" Fg increased with the length of the alkyl side chain when assessed by MoAb against Fg fragment D or E, whole Fg, or γ/γγ chain at the saturated concentration of adsorbed Fg (0.3 ug/cm2) and was significantly greater on PBMA than on PMMA. Adsorbed "native" Fg decreased with length of the alkyl side chain at a lower concentration of Fg ( |
