title: Cytotoxic properties of eosinophil granule major basic protein for tumor cells.
abstract: BACKGROUND
  Eosinophil granule major basic protein (MBP) mediates many eosinophil-associated immune functions and it adheres eosinophils to parasite targets.
  
  
  METHODS
  We compared the toxicities of MBP and melittin to K562 and HL-60 cells using five cytotoxicity methods.
  
  
  RESULTS
  Trypan blue staining, propidium iodide/ CellTrackertrade markGreen staining and incorporation of 14C-leucine assays indicated that MBP damages most cells by 1 h. In contrast, 51Cr and lactic dehydrogenase (LDH) release assays indicated that MBP damages most cells only at 20 h. All five methods indicated that melittin damages nearly all cells by 1 h. To resolve these discrepancies, the procedures were modified. Without cell transfer, dye staining methods showed that MBP produces very little cytotoxicity at 4 h. 51Cr and LDH assays, modified to mimic cell transfer, showed increased cytotoxicities at 4 h. The 14C-leucine assay modified by solubilization of cells with SDS and by trichloroacetic acid precipitation showed increased recovery of labeled protein and, thus, lower cytotoxicity, about 50%, at 4 h.
  
  
  CONCLUSIONS
  Overall, MBP's ability to cause molecular and cellular adhesion confounds cytotoxicity measurements. A modified 14C-leucine assay overcame MBP's adhesiveness and provided an accurate measure of cytotoxicity.
authors.affiliation: Departments of Immunology and Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
authors.forename: H
authors.initials: H
authors.lastname: Kubo
authors.forename: D A
authors.initials: DA
authors.lastname: Loegering
authors.forename: C R
authors.initials: CR
authors.lastname: Adolphson
authors.forename: G J
authors.initials: GJ
authors.lastname: Gleich
mesh_terms: D001798:Blood Proteins / Q000276:immunology*; D003594:Cytoplasmic Granules / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D047091:Eosinophil Granule Proteins; D004804:Eosinophils / Q000276:immunology* / Q000648:ultrastructure; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D009369:Neoplasms / Q000276:immunology*; D012260:Ribonucleases
chemical_list: D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D012260:Ribonucleases