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Effects of bilirubin and phototherapy on osmotic fragility and haematoporphyrin‐induced photohaemolysis of normal erythrocytes and spherocytes
Author(s) -
Bruzell Roll Ellen,
Christensen Terje,
Gederaas Odrun A
Publication year - 2005
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.2005.tb01818.x
Subject(s) - erythrocyte fragility , hereditary spherocytosis , haemolysis , bilirubin , albumin , medicine , hemolysis , red blood cell , red cell , endocrinology , immunology
Aim: To study the effects of phototherapy on erythrocyte haemolysis in vitro and to determine possible differences in sensitivity to phototherapy between normal erythrocytes and spherocytes. Methods: Erythrocytes from four normal healthy donors and two donors with hereditary spherocytosis were treated with bilirubin (160 μM) in the presence of human serum albumin in the molecular ratio bilirubin/albumin 0.8. Treated cells were maintained either in the dark or in blue light (450 nm, 8 mW/cm 2 , 30 min). The experimental light dose was comparable to 2 h of clinical phototherapy. The osmotic fragility of the treated cells was measured by scoring haemolysis in hypo‐osmolar solutions (0.10–0.90% NaCl). The sensitivity to photohaemolysis of cells pre‐treated with bilirubin (BR) and/or phototherapy was tested by exposing the cell suspensions to haematoporphyrin and UVA radiation. The delayed (18 h) photohaemolysis was measured by spectrophotometry. Results: Osmotic fragility, expressed as percentage haemolysis, of normal erythrocytes was more than doubled in the presence of BR combined with phototherapy ( n =6, p <0.05). In contrast, osmotic fragility of spherocytes was unaffected by either treatment ( n =8, p <0.05). Increased photohaemolysis was seen in spherocytes treated with BR ( n =13, p <0.05), phototherapy ( n =13, p <0.05) and a combination of the two agents ( n =13, p <0.05) compared with spherocytes without BR in the dark ( n =6). Conclusion: Bilirubin may make the plasma membrane of normal erythrocytes more fragile. Newborns with hereditary spherocytosis may be sensitive to phototherapy.