Influence of gamma irradiation and storage on apheresis platelets

Background and purpose: Gamma irradiation of platelet concentrates to preve nt graft-versus-host disease may inactivate contaminated lymphocytes and su bsequently inhibit the synthesis of cytokines in the apheresis platelets du ring storage. We investigated the influence of irradiation and storage on a pheresis platelets collected with the COBE Spectra or Fenwal CS-3000 Plus s ystems. Methods: Eleven units of apheresis platelets were collected with a COBE Spe ctra cell separator and another Ii units with a Fenwal CS-3000 Plus system. Each unit of apheresis platelets was divided into two equal parts: one was irradiated with 3000 cGy directly after blood donation, and the other sen ed as a control. Cell counts, platelet activation marker CD62 antigen, bloo d gas values, and supernatant concentrations of K+, Na+, lactate, glucose, interleukin-1 beta (IL-1 beta), IL-8, and tumor necrosis factor-alpha (TNF- alpha) were determined in paired samples on the day of collection (day 0) a nd after 5 days of storage (day 5). Results: No significant differences in white cell counts or TNF-alpha conce ntrations were noted between the irradiated and control platelets on day 0 or day 5, whereas the mean proportion of platelets expressing CD62P (22.65% vs 25%, p = 0.014) and the mean IL-1 beta (45.55 pg/mL vs 52.75 pg/mL, p = 0.004) and IL-8 concentrations (10.68 pg/mL vs 13.07 pg/mL, p = 0.015) wer e significantly lower in irradiated than control platelets on day 5. The 5- day storage significantly increased the mean proportion of platelets expres sing CD62P (25.00% vs 15.02%, p = 0.008), mean PO2 (116.34 mm Hg vs 98.07 m m Hg, p = 0.002), and mean concentrations of K+ (3.30 mmol/L vs 3.06 mmol/L , p < 0.001), lactate (15.12 mmol/L vs 3.23 mmol/L, p < 0.001), IL-1 beta ( 52.75 pg/mL vs 29.73 pg/mL, p = 0.001), and IL-8 (13.07 pg/mL vs 3.62 pg/mL , p < 0.001). Five-day storage also significantly decreased white cell coun t (0.18 x 10(8) vs 0.74 x 10(8), p < 0.001), PCO2 (19.38 mm Hg vs 50.51mm H g, p < 0.001), and concentrations of HCO3- (10.36 mmol/L vs 21.34 mmol/L, p < 0.001) and glucose (193.37 mg/dL vs 309.18 mg/dL, p < 0.001). Platelet c ounts and concentrations of IL-1 beta, IL-8, and TNF-alpha on day 0 did not differ significantly between control apheresis platelets collected with th e Fenwal CS-3000 Plus and those collected with COBE Spectra. The mean white cell count (1.29 x 10(8) VS 0.19 x 10(8), p = 0.002) and the proportion of platelets expressing CD62P (24.71% vs 7.09%, p < 0.001) on day 0, however, were significantly higher in the platelets collected with the Fenwal CS300 0-Plus than in those collected with the COBE Spectra. Conclusions: Gamma irradiation of apheresis platelets inhibits the expressi on of platelet CD62P and the secretion of IL-1<beta> and IL-8 after 5 days' storage.