JRG, Newal DR. Relaxin as an aetiological factor in diabetic embryopathy. Lancet 1988; i: 1428-30. 4. Weiss G, O’Byme EM, Steinetz BG. Relaxin: a product of the human
corpus luteum of pregnancy. Science 1976; 194: 948-49. 5. O’Byrne EM, Carriere BT, Sorensen L, et al. Plasma relaxin in pregnant women. J Clin Endocr Metab 1978; 47: 1106-10. 6. Quagliarello J, Slachter N, Steinetz B, et al. Serial relaxin concentrations in human pregnancy. Am J Obstet Gynecol 1979; 135: 43-44. 7. Olefsky JM, Saekow M, Kroc RL. Potentiation of insulin binding and insulin action by purified porcine relaxin. Ann NY Acad Sci 1982; 380: 200-15. 8. Jarrett JC, Ballejo G, Saleem TH, Tsibris JCM, Spellacy WN. The effect of prolactin and relaxin in insulin binding by adipocytes from pregnant women. Am J Obstet Gynecol 1984; 149: 250-55. 9. Pederson J. The pregnant diabetic and her newborn, 2nd edition. Baltimore: Williams and Wilkins, 1980. 10. Vasilenko P, Adams WC, Frieden EH. Comparison of systemic and uterine effects of relaxin and insulin in alloxan-treated, hyperglycemic rats. Proc Soc Exp Biol Med 1982; 169: 376-79. 11. Stewart MO, Whittaker PG, Persson B, et al. A longitudinal study of circulating progesterone, oestradiol, hCG and hPL dunng pregnancy in type I diabetic mothers. Br J Obstet Gynaecol 1989; 96: 415-23. 12. O’Byrne EM, Steinetz BG. Radioimmunoassay (RIA) of relaxin in sera of various species using an antiserum to porcine relaxin. Proc Soc Exp Biol
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SHORT REPORT We recommend that whole blood should be held at 22°C to make use of inherent bactericidal activity; leucocytes should then be removed.
when the temperature is below 17oc.s,7 In most blood transfusion services world wide, donor blood is cooled to 4°C within 6 h of collection to minimise bacterial
multiplication. In Amsterdam since 1987, all whole blood units have been stored at 22°C for 16-20 h before processing into components. We have investigated the effect of this step on bactericidal activity of the donor leucocytes in whole blood. If leucocytes with internalised bacteria were then removed, bacterial growth would be reduced. A strain of Y enterocolitica 03 (IP 134, the National Institute for Public Health, Utrecht, Netherlands) was held in frozen stock; an experiment it was cultured for 24 h. Dilutions were prepared in sterile phosphate-buffered saline. Immediately after collection thirty pools of 3 bags of whole blood with identical blood groups were made and inoculated under aseptic conditions with 2 x 101-3 x 10’ colony-forming units (CFU)/ml of Yenterocolitica. (In donors without serious disorders the number of circulating Y enterocolitica is assumed to vary from 1 to 100 CFU/ml.) Each pool was split into the three original bags. One bag from each pool was processed to RBC after a 6 h hold at 4°C according to the methods of the American Association of Blood Banks (Manual 1991). The other two bags were processed to buffy-coat-depleted (BCd)-RBCs after a 20 h hold at 22OC,9 then one bag of BCd-RBC was filtered through a cellulose acetate filter column (Cellselect, NPBI, Emmercompascuum, Netherlands) within 24 h of collection to give leucocyte-depleted (Ld)-RBC.lO The filtration procedure was done in a closed system by welding the tubing of the filter and the blood bag together with a sterile connection device.lO Saline-adenine-glucose-mannitol solution was added to all types of RBC so they could be stored for 5 weeks at 4°C.° 1 unit of RBC contained 2-4 x 109 leucocytes (100% of original value), BCd-RBC 0-8 x 109 leucocytes (about 30% of original value), and Ld-RBC fewer than 0-01 x 109 leucocytes (0-05% of original value). From each type of RBC concentrate in each pool a 5 ml sample for
culture was taken at week 0 (24 h after inoculation) then at weeks 1, 2,3,4, and 5. When more than 105 CFU/ml were present, that RBC concentrate was no longer tested. From 1 0,0 1,001,andOOOl ml RBC concentrate samples, triplicate pour plates were prepared with 20 ml tryptone soya agar containing vancomycin (1 mg/1000 ml
Removal of Y enterocolitica was better in Ld- RBC than in BCd-RBC or RBC at any time point (p < 003-0001, table). Ld-RBC showed growth after longer storage times than the other preparations; BCd-RBC, in turn, showed growth after longer storage times than RBC. With contamination of less than 3 x 102 CFU/ml, reduction of storage time of RBC from 5 to 3 weeks would reduce multiplication of Y enterocolitica. However, to eliminate Y enterocolitica, leucocyte depletion after holding whole blood at 22°C was the most effective method; use of 5-week storage times of Ld-RBC could be continued. To reduce bacterial contamination in routine blood bank procedures, leucocytes should be able to function (ie, carry out phagocytosis and killing) for several hours at temperatures of 18-24°C. The time for which whole blood should be held at 22°C could be between 6 and 24 h. For logistic reasons an overnight hold for 16-20 h is convenient, and all units of blood can be processed during the next day. Subsequent removal of leucocytes by filtration is the best way to avoid growth of Y enterocolitica. Furthermore, transfusion of leucocyte-depleted blood products will reduce HLA immunisation, and prevent transmission of cytomegalovirus and human T-cell leukaemia virus. We thank Ms N. Schram-Bakker and Mr W.
Schaasberg for statistical
analysis. REFERENCES 1.
Yersinia enterocolitica bacteremia and endotoxin shock associated with red blood cell transfusions—United States, 1991. Morbid Mortal
Weekly Rep 1991; 40: 176-78. Hoppe PA. Interim measures for detection of bacterially contaminated red cell components (editorial). Transfusion 1992; 32: 199-201. 3. Goldman M, Blajchman MA. Blood product associated bacterial sepsis. Trans Med Rev 1991; V: 73-83. 4. Stossel TP. Phagocytosis recognition and ingestion. Semin Hematol 1975; 2.
12: 83-116. 5. Peterson PK, Verhoef
J, Quie PG. Influence of temperature on opsonization and phagocytosis of staphylococci. Infect Immun 1977; 15: 175-79.
Hogman CF, Gong J, Eriksson L, Hambraeus A, Johansson CS. White cells protect donor blood against bacterial contamination. Transfusion 1991; 31: 620-26. FS, Schneider DL. The activation of the human neutrophil
respiratory burst occurs only at temperature above 17°C: evidence that activation requires membrane fusion. Biochem Biophys Res Commun 1985; 132: 696-701. RNI, Reesink HW, Dekker WJA, Fijen FJ. Preparation of
leukocyte-poor platelet concentrates from buffy coats. I. Special inserts for centrifuge cups. Vox Sang 1987; 53: 203-07. 9. Pietersz RNI, de Korte D, Reesink HW, Dekker WJA, van den Ende A, Loos JA. Storage of whole blood for up to 24 hours at ambient temperature prior to component preparation. Vox Sang 1989; 56: 145-50. 10. Pietersz RNI, Reesink HW, de Korte D. Storage of leukocyte-poor red cell concentrates: filtration in a closed system using a sterile connection device. Vox Sang 1989; 57: 29-36. ADDRESSES. Red Cross Blood Bank, Amsterdam (R. N I. Pietersz, MD, H W. Reesink, MD, W J. A Dekker) and Department of Slotervaart Microbiology, Hospital, Amsterdam, The R I Netherlands (W. Pauw, MD, L. Buisman) Correspondence to Dr N Pietersz, Red Cross Blood Bank Amsterdam, Postbox 9137, 1006 AC Amsterdam, The Netherlands.