title: Removal of donor human leukocyte antigen class I proteins with papain: translation for possible whole organ practices.
abstract: BACKGROUND
  Papain is a protease with potential use in transplantation because of its targeted capacity to selectively remove human leukocyte antigen (HLA) class I proteins from donor human cells. However, its proteolytic activity has not been studied under conditions suitable for use in perfusing donor organs, namely, under a temperature of 4°C and dissolution in Belzer-UW solution.
  
  
  METHODS
  We test papain's HLA class I removing activity under recognized whole organ transplant conditions of lowered temperature. The activity of papain's substrate selectivity was tested using both a test substrate (casein) and fresh peripheral blood lymphocytes (PBLs). The activity of papain was also tested at 4°C, the temperature of whole organ storage.
  
  
  RESULTS
  We found that papain at a range of concentrations is nearly as active in cleaving the test substrate in Belzer-UW solution as in distilled water. In distilled water, papain is as active in cleaving a test substrate at a temperature of 4°C as compared to its optimal temperature of 37°C, if the incubation time is extended from 10 min to 3 hr. This finding also holds true if papain is dissolved in Belzer-UW solution. In peripheral blood lymphocytes, papain cleaved off HLA class I proteins as effectively at 4°C as at 37°C, provided the incubation time was also extended to 3 hr.
  
  
  CONCLUSIONS
  These findings suggest that papain's targeted enzymatic cleavage of donor HLA class I has potential use in the whole organ transplant setting with retained activity at lower temperatures and when activated and dissolved in Belzer-UW solution.
authors.affiliation: Laboratory of Immunobiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Mera
authors.forename: Denise L
authors.initials: DL
authors.lastname: Faustman
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000493:Allopurinol / Q000494:pharmacology; D002364:Caseins / Q000378:metabolism; D003080:Cold Temperature; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000494:pharmacology; D006680:HLA Antigens / Q000276:immunology / Q000378:metabolism*; D006648:Histocompatibility / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007519:Isoantigens / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology / Q000276:immunology; D019188:Organ Preservation Solutions / Q000494:pharmacology; D016377:Organ Transplantation / Q000009:adverse effects*; D010206:Papain / Q000378:metabolism / Q000494:pharmacology*; D011887:Raffinose / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D002364:Caseins; D006680:HLA Antigens; D007166:Immunosuppressive Agents; D007328:Insulin; D007519:Isoantigens; D019188:Organ Preservation Solutions; C055206:University of Wisconsin-lactobionate solution; D000493:Allopurinol; D010206:Papain; D005978:Glutathione; D000241:Adenosine; D011887:Raffinose