A rapid stain for Pneumocystis.

Step in procedure Supernatant haemoglobin (g) After thawing 0 45 First wash 1 6 Second wash 0-45 Third wash 0-12 Final product 0-023 After incubation 0-05 stability of the red cell preparation after incubation at 37°C for 30 minutes. Recovery was calculated from the supernatant haemoglobin in relation to the initial total haemo-globin after thawing (table 2). Mean (SD) recovery was 70% (13 3), range 45-82% (n = 16). The mean (SD) volume of packed red cells available for use was 17 ml (6) (n = 16). All recoveries were sterile. To date red cells from eight accredited donors have been stored in small aliquots for use in a five year boosting programme of 20 volunteers to maintain plasma anti-D concentrations of at least 50 IU/mI. Over the past two years 35 doses have been given to 20 volunteers with no untoward effects. Small volumes (0 1-0-5 ml) were given intravenously. The frequency of administration depended on the initial anti-D value and the magnitude of the immune response to each booster injection. Discussion This method allows the storage and recovery of small aliquots of fully phenotyped red cells from accredited donors and ensures that each volunteer is boosted repeatedly with red cells from the same donor over the whole five year period of the planned boosting and plasmapheresis programme. The volume of red cells recovered from any one aliquot was sufficient in all cases for boosting any number of volunteers. The technique is safe and conforms to international criteria of good manufacturing practice. Volunteers responded well to repeated small boosting doses with no adverse reactions. We thank Mrs S Balmer for typing the manuscript. References 1 World Health Organisation. The collection, fractionation, quality control and uses of blood and blood products.