Background/Case Studies: Irradiation of amotosalen/UVA pathogen reduced (PR) platelets (plts) is not required. However, PR plts in the clinical SPRINT study (Blood 2004:104:1535-1541) underwent irradiation before transfusion. It is not known if irradiation negatively effects PR plts properties or function in vitro. Moreover, the in vitro effect of pathogen reduction should be taken into consideration. The effects of irradiation on PR plts properties vs. that of non-PR plts were compared.
Study
Design/Methods: Collection of apheresis plts from healthy donors was performed using the Amicus Separator with PAS. Collections underwent a standard PR process using the amotosalen/UVA Intercept Blood System. The PR plt was split: half was irradiated with 2500 cGy via a Cesium-137 irradiator or by X-Ray. PR plt properties and function of irradiated vs. non-irradiated were measured at Days 1 and 5. Parameters examined included plt concentration, MPV, pH, CD62P, and Annexin V binding. Aggregometry using TRAP-6 and flow cytometry was performed. To control for the effects of pathogen reduction on plts and inter-donor variability, the same donors were asked to return for a repeat collection >4 weeks later. Their apheresis collections underwent the same process as above, but without PR to produce standard (conventional) non-PR plts as controls.
Results/Findings: Six donors (4F/2M, 31-79 years old, 3 group A, 2 group O and 1 AB, ethnically diverse), each donated twice. Bags measured 359-394ml. All bags were bacterial cultured negative at 7 days. Plt in vitro parameters on day 5 of storage are shown in Table 1. All parameters were equal at Day 1 due to the plt splitting. No significant differences were observed between control, PR or irradiated arms in % plt loss, MPV or aggregation measures. Significant decreases in pH, increases in % positivity in CD62 (activation) and Annexin V (apoptosis) were measured in control vs. PR and PR irradiated; there were no significant differences between PR and PR Irradiated plts after 5 days Conclusions: In vitro measures of decreased pH, increased activation and apoptosis and a trend toward decreased aggregation were observed in PR plts compared to conventional plts over 5-day storage, but pre-storage irradiation did not further impact plt measures of plt quality. As a clinical correlate, the negative effect of the PR process alone may influence plt increments. This abstract reflects the views of the authors and should not be construed to represent FDA's or NIH views or policies.
Importance of research: A transfusion service may choose to irradiate PR platelets before storage. Though the amotosalen/UVA pathogen reduction process had a detrimental impact on in vitro platelet properties, irradiation produced no further negative effect after 5-day storage. The clinical correlate of the in vitro finding of increased markers of activation and apoptosis in PR platelets, regardless of irradiation, may be lower PR platelet increments with transfusion of PR platelets compared to conventional platelets.
