title: Antibody-mediated glycophorin C coligation on K562 cells induces phosphatidylserine exposure and cell death in an atypical apoptotic process.
abstract: BACKGROUND
  Glycophorin C (GPC) is necessary in the maintenance of red blood cell structure. Severe autoimmune hemolytic anemia and hemolytic disease of the fetus and newborn (HDFN) have been associated with Gerbich (Ge) blood group system antigens expressed on GPC. Previous in vitro studies with cord blood progenitor cells have shown that anti-Ge suppresses erythropoiesis.
  
  
  METHODS
  Here, we evaluated the K562 erythroleukemic cell line to study the cellular effects of a murine anti-GPC. Cell proliferation was evaluated after treatment with anti-GPC. Flow cytometry was used to evaluate exofacial phosphatidylserine (PS) expression and cell viability (propidium iodide binding). Cell morphology was evaluated under light microscopy with cytospin preparations stained with May-Grünwald Giemsa.
  
  
  RESULTS
  Anti-GPC dramatically inhibited K562 proliferation and increased PS expression, consistent with cytoplasmic blebbing, suggesting evidence of apoptosis. Z-VAD-FMK, an inhibitor of classical apoptosis, was unable to reverse the suppressive effect of anti-GPC. However, hemin was able to attenuate growth suppression.
  
  
  CONCLUSIONS
  Together, the data suggest that anti-GPC suppresses erythroid proliferation through the induction of nonclassical apoptosis.
authors.affiliation: Immunohematology Reference Laboratory, BloodCenter of Wisconsin, Milwaukee, Wisconsin; Pathology & Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada; Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada; Research & Development, Canadian Blood Services, Toronto, Ontario, Canada.
authors.forename: Duncheng
authors.initials: D
authors.lastname: Wang
authors.forename: Eva
authors.initials: E
authors.lastname: Seto
authors.forename: Jenny
authors.initials: J
authors.lastname: Shu
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Micieli
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Fernandes
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Denomme
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017209:Apoptosis; D049109:Cell Proliferation; D004920:Erythropoiesis; D005047:Etoposide / Q000494:pharmacology; D006021:Glycophorins / Q000276:immunology / Q000502:physiology*; D006801:Humans; D020014:K562 Cells; D010718:Phosphatidylserines / Q000378:metabolism*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000911:Antibodies, Monoclonal; D006021:Glycophorins; D010718:Phosphatidylserines; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D005047:Etoposide