BACKGROUND: epsilon-Poly-l-lysine (epsilon-PLL) is a polypeptide comprising approximately 30 l-lysine subunits generated by bond formation between alpha-carboxy and epsilon-amino groups. It is an approved antimicrobial food preservative in Japan. However, the efficacy of epsilon-PLL as an antibacterial additive for storage of human platelet concentrates (PCs) is not known. STUDY DESIGN AND METHODS: Staphylococcus aureus, Bacillus cereus, and Klebsiella oxytoca (20 colony-forming units/mL) were inoculated into 100% plasma PCs or PCs containing 80% platelet (PLT) additive solution with 5.0 mmol/L potassium and 1.5 mmol/L magnesium (PAS-IIIM) and 20% plasma (PAS-IIIM PCs). Next, a range of epsilon-PLL concentrations up to 200 and 50 microg/mL were added to plasma PCs and PAS-IIIM PCs, respectively, and the bacterial count was determined on Days 1, 2, 5, and 8. The quality of the PCs was also determined. RESULTS: Bacterial growth was inhibited at epsilon-PLL concentrations of 200 and 50 microg/mL in the plasma and PAS-IIIM PCs after 8 days of incubation. The percentage of CD62P-positive PLTs was higher in plasma PCs treated with 200 microg/mL epsilon-PLL and in PAS-IIIM PCs treated with 50 microg/mL epsilon-PLL than in the respective controls without epsilon-PLL. There were no remarkable differences in the other variables, that is, PLT number, mean PLT volume, pH, aggregability, percentage of PAC-1-positive cells, lactate dehydrogenase release, and plasma K and Na concentrations between the epsilon-PLL-treated PCs and the controls. CONCLUSIONS: epsilon-PLL inhibited the growth of bacteria in the PCs and did not considerably affect the quality of PCs, except CD62P expression. Further studies are required to estimate the in vivo effectiveness and safety of epsilon-PLL-treated PCs.
BACKGROUND:epsilon-Poly-l-lysine (epsilon-PLL) is a polypeptide comprising approximately 30 l-lysine subunits generated by bond formation between alpha-carboxy and epsilon-amino groups. It is an approved antimicrobial food preservative in Japan. However, the efficacy of epsilon-PLL as an antibacterial additive for storage of human platelet concentrates (PCs) is not known. STUDY DESIGN AND METHODS: Staphylococcus aureus, Bacillus cereus, and Klebsiella oxytoca (20 colony-forming units/mL) were inoculated into 100% plasma PCs or PCs containing 80% platelet (PLT) additive solution with 5.0 mmol/L potassium and 1.5 mmol/L magnesium (PAS-IIIM) and 20% plasma (PAS-IIIM PCs). Next, a range of epsilon-PLL concentrations up to 200 and 50 microg/mL were added to plasma PCs and PAS-IIIM PCs, respectively, and the bacterial count was determined on Days 1, 2, 5, and 8. The quality of the PCs was also determined. RESULTS: Bacterial growth was inhibited at epsilon-PLL concentrations of 200 and 50 microg/mL in the plasma and PAS-IIIM PCs after 8 days of incubation. The percentage of CD62P-positive PLTs was higher in plasma PCs treated with 200 microg/mL epsilon-PLL and in PAS-IIIM PCs treated with 50 microg/mL epsilon-PLL than in the respective controls without epsilon-PLL. There were no remarkable differences in the other variables, that is, PLT number, mean PLT volume, pH, aggregability, percentage of PAC-1-positive cells, lactate dehydrogenase release, and plasma K and Na concentrations between the epsilon-PLL-treated PCs and the controls. CONCLUSIONS: epsilon-PLL inhibited the growth of bacteria in the PCs and did not considerably affect the quality of PCs, except CD62P expression. Further studies are required to estimate the in vivo effectiveness and safety of epsilon-PLL-treated PCs.