Plasma components protect erythrocytes against experimental haemolysis caused by mechanical trauma and by hypotonicity.

To examine the ability of plasma to prevent haemolysis caused by mechanical trauma and by hypotonicity, in-vitro experiments were carried out. Human red blood cells (RBC) were agitated with glass beads at 37 degrees C for 18 h in isotonic tris-buffered saline (TBS) or with additions of test substances to TBS. RBC were incubated for 18 h at 37 degrees C in a stationary water-bath to test effects of hypotonic solutions. Release of haemoglobin was quantitated by measuring optical density of supernates at 412 nm in a spectrophotometer. Agitation of RBC with glass beads in TBS resulted in release of about 30% of haemoglobin, and this haemolysis was inhibited by autologous plasma. Components of plasma that contributed to protection against mechanical haemolysis were albumin, a supernatant of plasma after heating to 100 degrees C that was albumin-free, and a heat-stable extract of fresh frozen plasma (FFP), whereas little or no protection was provided by gamma-globulin, haptoglobin, ceruloplasmin or alpha-2-macroglobulin. Relative viscosity of solutions containing plasma or dextran correlated poorly with protection against mechanical haemolysis. Hypotonic solutions of plasma and addition of the extract of FFP to TBS caused reductions in rates of haemolysis when compared to corresponding osmolalities of solutions of TBS. These results, which showed protective effects of plasma and plasma components against mechanical and hypotonic haemolysis, suggest that a deficiency of protective factors in plasma of patients could contribute to the development of haemolytic anaemia.