English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Complement appears to be involved in the destruction of platelets in certain clinical disorders, such as quinidine purpura and post-transfusion purpura. In both disorders, the classical complement sequence is activated by antigen-antibody complexes. It has been suggested that the terminal components of the complement sequence insert into the hydrophobic core of cell surface membranes and that this process leads to cell lysis. Fluidity is a fundamental property of lipids within the membrane's hydrophobic core. To examine the interaction of complement with membranes, we investigated the effect of complement activation on the fluidity of human platelet membranes. Complement was fixed to platelets using a post-transfusion purpura antibody, and membrane lipid fluidity was assessed in terms of fluorescence anisotropy using two fluorescent probes, 1,6-diphenyl-1,3,5-hexatriene and 9-(12-anthroyl) stearic acid. Microviscosity, expressed in poise, was derived from the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene.Post-transfusion purpura antibody plus complement made platelet membranes more fluid as evidenced by a 21% decrease in anisotropy and a 35% decrease in microviscosity of platelets at 37 degrees C, and this was associated with platelet lysis ((51)Cr release). Complement damage to platelets was accompanied by a 10-15% increase in DeltaE, the fusion activation energy for microviscosity, indicating that complement not only decreased membrane microviscosity but also made membrane lipids less ordered. These changes were consistent and rapid, with platelet lysis and the reduction in microviscosity being half-maximal by 6 min. They were prevented by inactivation of complement with heat or with EDTA, and they were not observed when C5-deficient plasma was used as the complement source. Qualitatively similar changes in platelet membrane fluidity were observed when complement was fixed to platelets by a quinidine-dependent anti-platelet antibody rather than by post-transfusion purpura antibody. Post-transfusion purpura antibody plus complement also decreased the microviscosity of isolated platelet membranes. Moreover, the lipids extracted from platelets lysed by complement had a 22% decrease in microviscosity (P &lt; 0.01), with no associated changes in the amount of cholesterol relative to phospholipid or in the amounts of the various phospholipids. These studies demonstrate that lipids within the hydrophobic core of platelet membranes damaged by complement become more fluid, and this is associated with platelet lysis. These findings are consistent with the concept that the insertion of the terminal complement components into the platelet membrane bilayer perturbs lipid-lipid interactions within the membrane's hydrophobic core.

Increased Fluidity of Human Platelet Membranes during Complement-Mediated Immune Platelet Injury