Background and Objectives Changes in in vitro platelet quality parameters during platelet storage are associated with a decrease of in vivo platelet viability after platelet transfusion. Many attempts have been made to identify the most predictable in vitro parameters for in vivo performance. We used a riboflavin-based ultraviolet (UV) light treatment process designed to inactivate pathogens and white blood cell (WBC) contaminants in blood products as a model system in which to study the correlation of in vitro cell quality with in vivo viability. Materials and MethodsPlatelet products ( n = 18) were collected by a standard Trima apheresis procedure and treated with one of three dose levels of UV light (0, 7·2 or 12·4 J/ml) in the presence of 50 µ M riboflavin. Lactate production, glucose consumption and P-selectin expression, pH, pCO 2 , pO 2 , hypotonic shock response and swirl were measured during 5 days of platelet storage post-UV/RB treatment. Aliquots of these products were radiolabelled on day 5 of storage and were subsequently used to determine platelet recovery and survival time in autologous subjects. ResultsThe responses of in vitro cell quality were observed to occur in a UV dosedependent manner. Lactate production and pH were identified as the parameters most strongly correlated with platelet in vivo recovery, which ranged from 5 to 82%. The correlation coefficients ( r ) for lactate production and pH with in vivo recovery in human subjects were 0·9090 and 0·8831 with P -values of 0·007 and 0·031, respectively. Lactate production and pH were also found to be correlated with platelet survival time, with correlation coefficients of 0·8063 and 0·8384 (the P values were 0·01 and 0·001, respectively).Conclusions Using conditions of riboflavin-based UV light treatment, lactate production and pH were identified as having the highest correlations with recovery and survival of radiolabelled platelets in healthy subjects.Key words: in vitro platelet quality, in vivo platelet recovery, platelet survival, platelet viability prediction, UV light treatment.

The implementation of enhanced education and selection policies in South Africa was associated with decreased prevalence of HIV-1 in blood donations.

Implementation of routine NAT blood screening would allow elimination of HIV-1 p24 antigen testing and improve the safety of the blood supply in South Africa. However, the cost-benefit ratio of introducing such an expensive technology in a country with a limited health budget will have to be carefully considered.

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The prevalence of GBV-C infection in voluntary blood donors and in groups at high risk for parenteral exposure to infectious agents was studied. The high risk groups included chronic renal failure patients on haemodialysis, renal transplant patients and haemophiliacs from Gauteng. The presence of GBV-C RNA in these populations was determined using reverse transcription polymerase chain reaction (RT-PCR) in the 5' non-coding region (NCR) of the virus. Of the blood donors, 11.1% (95% CI 7.6, 15.8) were positive, whereas 23.8% (95% CI 12.6, 40.2) of haemodialysis patients and 23.5% (95% CI 15.9, 33.3) of the haemophiliacs were infected with GBV-C. The highest proportion of infection was in the renal transplant patients, where 41.2% (95% CI 35.1, 47.7) were found to have circulating GBV-C RNA. Serological markers for hepatitis B (HBV) and hepatitis C viruses (HCV) were also measured as indicators of other hepatitis viruses with important parenteral transmission routes. Of the GBV-C positive blood donors, 3.6% were also HBsAg positive and none were positive for HCV. The GBV-C positive patients on haemodialysis were not positive for either HBsAg or antibodies to HCV, but had evidence of past infection with HBV since 40% were anti-HBc positive. The greatest proportion of HCV positives was in the haemophiliac group, 91.3%, none of these were HBsAg positive but 39.1% had anti-HBc. In the GBV-C positive renal transplant patients, 4% had HBsAg, 13.3% had anti-HBc and 2.1% had antibodies to HCV. This is the first report describing the prevalence of GBV-C in South African populations.