Agglutination of like-charged red blood cells induced by binding of β2-glycoprotein I to outer cell surface

Plasma protein-mediated attractive interaction between membranes of red blood cells (RBCs) and phospholipid vesicles was studied. It is shown that β2-glycoprotein I (β2-GPI) may induce RBC discocyte–echinocyte–spherocyte shape transformation and subsequent agglutination of RBCs. Based on the observed β2-GPI-induced RBC cell shape transformation it is proposed that the hydrophobic portion of β2-GPI molecule protrudes into the outer lipid layer of the RBC membrane and increases the area of this layer. It is also suggested that the observed agglutination of RBCs is at least partially driven by an attractive force which is of electrostatic origin and depends on the specific molecular shape and internal charge distribution of membrane-bound β2-GPI molecules. The suggested β2-GPI-induced attractive electrostatic interaction between like-charged RBC membrane surfaces is qualitatively explained by using a simple mathematical model within the functional density theory of the electric double layer, where the electrostatic attraction between the positively charged part of the first domains of bound β2-GPI molecules and negatively charged glycocalyx of the adjacent RBC membrane is taken into account.