Assessment of the optimal anticoagulant solution for storage of whole blood samples prior to measurement of platelet-associated IgG.

The complexity of assays used to measure platelet-associated IgG (PAIgG) often requires blood samples to be sent to a central laboratory, In order to determine the optimal storage conditions, we measured PAIgG, platelet recovery, and platelet size serially over several days in whole blood samples obtained from healthy individuals. Blood was collected into EDTA, acid-citrate-dextrose (ACD) and citrate-phosphate-dextrose-adenine (CPD-A) with and without the fixative paraformaldehyde (P). The level of PAIgG remained with normal limits in all samples stored for up to six days in the ACD, the CPD-A and the CPD-A-P samples. The least drop in platelet count and change in platelet size occurred in the ACD and CPD-A samples. Blood collected into EDTA plus paraformaldehyde was less satisfactory, with PAIgG rising by day three in some samples, and a decline in the platelet count occurring by day two. Specimens collected into EDTA alone were least satisfactory, with a rise in PAIgG by 24 hours after collection. Collection of whole blood into either ACD or CPD-A and storage at 22 degrees C allows a good recovery of platelets whose level of PAIgG is unchanged for up to six days.