Recombinant granulocyte colony-stimulating factor (r-GCSF) is used in autologous bone marrow/peripheral blood progenitor cell transplantation (ABMT/PBPC) to shorten the period of neutropenia. As these patients require platelet transfusions, their sera may be monitored for the presence of platelet/human leukocyte antigen (HLA) antibodies. Sera of some patients on r-GCSF (16 μg/kg/day) became difficult to evaluate in vitro for the presence of HLA and platelet antibodies because of apparently anomalous reactions in solid phase red cell adherence (SPRCA) assays. SPRCA tests were positive only when platelets were adhered to the polystyrene plates in the presence of glucose; when other simple sugars were used, the patients’ sera failed to react. HLA Bw6-positive platelets were more likely than HLA Bw6-negative platelets to be reactive (p < .001). The transfusion of HLA Bw6-positive platelets to patients displaying this in vitro reactivity (positive patients) resulted in a 50 percent lower corrected count increment (CCI) than those given to patients without it (negative patients; p = <.001). When all transfusions were considered, the CCI for those of the positive patients was decreased 73 percent when compared to the control patients (p = .0005). The presence of the antibody also was associated with a twofold increase in the number of platelet transfusions given (p = .0005). ABMT/PBPC patients receiving r-GCSF may develop unexpected reactions on SPRCA antibody screens and poor responses to transfusion of Bw-6-positive platelets. Immunohematology 2001;17:63–69.
