Preparation of IgA-deficient platelets.

The IgA-deficient patient presents a difficult transfusion problem, particularly if he or she has previously been immunized and has formed IgA antibodies. Blood components from IgA-deficient donors may be used safely but are often not accessible to transfusion facilities. A satisfactory red cell component may be obtained by standard freezing and washing methods. There is no comparable platelet concentrate that uniformly affords protection against anti-IgA-mediated reactions. A method has been developed for the preparation of an IgA-deficient platelet concentrate by washing with citrate-buffered saline. Platelets prepared in this manner were transfused successfully to an IgA-deficient patient with a history of anaphylaxis related to transfusion. It was further demonstrated that the removal of IgA is enhanced if platelets are washed within 48 hours of collection. When platelets were stored for more than 48 hours, similar washing techniques resulted in significantly higher levels of IgA in the platelets washed with either buffered (p = 0.004) or unbuffered (p = 0.0002) saline. Platelets washed with unbuffered saline (pH 4.5-5.5) contained substantially more IgA than did platelets washed in a similar manner with citrate-buffered saline (pH 6.5-6.8) (p = 0.001).