The resistance to physiological shear stresses of the erythrocytic rosettes formed by cells infected with Plasmodium falciparum

Resetting forces are believed to be an important contributor to the microci rculatory obstruction that occurs in malaria caused by Plasmodium falciparu m. In this study, rosettes of erythrocytes from cultures of this parasite w ere suspended in different media and exposed to shear stresses correspondin g to those encountered on the arterial and venous sides of the human circul ation. The rosettes formed by infected erythrocytes in malaria culture medi um containing 10% AB serum were disrupted easily (approximately 50% being b roken) when exposed to very low shear stresses of <0.5 Pa. However, use of higher concentrations of serum strengthened the resetting binding forces co nsiderably. Suspension of rosettes in a viscous colloid (e.g, dextran) incr eased the adherence forces between infected and uninfected red cells. The r esults indicate that rosettes do resist the physiological shear forces that are encountered in the venular side of the circulation and could thus cont ribute to microvascular obstruction in falciparum malaria.