Interaction of dilauroylglycerophosphocholine with erythrocytes: pre-hemolytic events and hemolysis.

The process of interaction of dilauroylglycerophosphocholine with erythrocytes that eventually results in hemolysis was examined. 1. The rate of uptake of dilauroylglycerophosphocholine by human erythrocytes was rather slow, but increased with increasing temperature. 2. The first observable change of human erythrocytes induced by dilauroylglycerophosphocholine was a morphological change from discocytes to spheroechinocytes. This change preceded K+ leakage. 3. Adsorption of dilauroylglycerophosphocholine to human erythrocytes caused K+ leakage. The rate of K+ leakage was also temperature-dependent. The temperature-dependence was due to the temperature-dependence of lipid uptake, because in order to cause K+ leakage a given amount of dilauroylglycerophosphocholine must be bound to the erythrocytes, irrespective of the temperature. 4. The temperature-dependence of hemolysis of human erythrocytes was different from that of pre-hemolytic events (morphological change, adsorption of lipids and K+ leakage). Hemolysis was rapid below 10 and above 37 degrees C, but slow at about 25 degrees C. The hemolysis observed below 10 degrees C seemed to be a 'colloid osmotic lysis', since it occurred immediately after K+ leakage, but the hemolysis above 37 degrees C may not be a colloid osmotic lysis. Above 37 degrees C, additional binding of dilauroylglycerophosphocholine to the erythrocyte membrane may cause hemolysis by a different mechanism from that working below 10 degrees C. 5. Above 25 degrees C, most human erythrocytes are resistant to colloid osmotic lysis induced by dilauroylglycerophosphocholine. It can be concluded that human erythrocytes are composed of two types of population, one resistant, and one sensitive to colloid osmotic lysis. The mechanism of the resistance was sensitive to temperature, pH and various sulfhydryl agents. 6. Pig erythrocytes were hemolysed immediately after K+ leakage even above 25 degrees C, indicating that they were sensitive to a colloid osmotic mechanism over the whole temperature range tested. Pig erythrocytes may lack the 'mechanism' giving resistance to colloid osmotic lysis. The process of hemolysis of erythrocytes by dilauroylglycerophosphocholine is shown schematically.