Hemolysis

Hemolysis or haemolysis (/hiːˈmɒlɪsɪs/), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo or in vitro (inside or outside the body). Hemolysis or haemolysis (/hiːˈmɒlɪsɪs/), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo or in vitro (inside or outside the body). One cause of hemolysis is the action of hemolysins, toxins that are produced by certain pathogenic bacteria or fungi. Another cause is intense physical exercise. Hemolysins damage the red blood cell's cytoplasmic membrane, causing lysis and eventually cell death. Hemolysis inside the body can be caused by a large number of medical conditions, including many Gram-positive bacteria (e.g., Streptococcus, Enterococcus, and Staphylococcus), some parasites (e.g., Plasmodium), some autoimmune disorders (e.g., drug-induced hemolytic anemia), some genetic disorders (e.g., Sickle-cell disease or G6PD deficiency), or blood with too low a solute concentration (hypotonic to cells). Hemolysis can lead to hemoglobinemia due to hemoglobin released into the blood plasma, which plays a significant role in the pathogenesis of sepsis and can lead to increased risk of infection due to its inhibitory effects on the innate immune system. Many species of the genus Streptococcus cause hemolysis. Streptococcal bacteria species are classified according to their hemolytic properties. Note that these hemolytic properties are not necessarily present in vivo. The genus Enterococcus includes lactic acid bacteria formerly classified as gamma-hemolytic Group D in the genus streptococcus (see above), including E. faecilis (S. faecalis), E. faecium (S. faecium), E. durans (S. durans), and E. avium (S. avium). Staphylococcus is another Gram-positive cocci. S. aureus, the most common cause of 'staph' infections, is frequently hemolytic on blood agar. Because the feeding process of the Plasmodium parasites damages red blood cells, malaria is sometimes called 'parasitic hemolysis' in medical literature. Hemolytic disease of the newborn is an autoimmune disease resulting from the mother's antibodies crossing the placenta to the fetus. This most often occurs when the mother has previously been exposed to blood antigens present on the fetus but foreign to her, through either a blood transfusion or a previous pregnancy.