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Platelet refractoriness and alloimmunization in pediatric oncology and bone marrow transplant patients
D E Hogge1, M McConnell, C Jacobson
1Cell Separator Unit, Vancouver Hospital and Health Sciences Centre, British Columbia, Canada.
Insights
Platelet refractoriness and alloimmunization are observed in pediatric oncology patients, with lower incidence in acute myelogenous leukemia. Routine white cell reduction did not significantly impact these rates.
Area of Science:
- Pediatric Hematology
- Oncology
- Transfusion Medicine
Background:
- Multiply transfused pediatric oncology and bone marrow transplant patients are at risk for platelet refractoriness and alloimmunization.
- Evaluating the impact of routine white cell reduction on these complications is crucial.
Purpose of the Study:
- To determine the incidence of platelet refractoriness and alloimmunization in multiply transfused pediatric oncology and bone marrow transplant patients.
- To assess the effect of routine white cell reduction on these incidences.
Main Methods:
- Retrospective analysis of 128 children's platelet transfusion records.
- Calculation of mean corrected count increments (CCIs) for random-donor and HLA-matched platelet transfusions.
- Monitoring for lymphocytotoxic antibodies (LCTAbs).
Main Results:
- Overall platelet refractoriness (CCI < 7.5) was 37%.
- Patients with acute myelogenous leukemia showed a significantly lower incidence (17%) of low CCIs.
- Routine white cell reduction did not significantly alter the incidence of LCTAbs or low CCIs.
Conclusions:
- Alloimmunization and platelet refractoriness occur in pediatric oncology/BMT patients, but are less common in AML.
- Positive LCTAbs predict poor response to random-donor platelets; HLA-matched platelets improve CCIs.
- Routine white cell reduction filters have not yet eliminated alloimmunization in this patient group.
Background:
The purposes of this study were to determine the overall incidence of platelet refractoriness and alloimmunization among multiply transfused children on a medical oncology and bone marrow transplant service and to evaluate the effect of routine white cell reduction in blood components on that incidence.
Study Design And Methods:
The platelet transfusion records of 128 consecutive children admitted to the hospital and requiring blood component support for the treatment of disease were evaluated retrospectively. Mean corrected count increments (CCIs) for each patient were calculated for all random-donor platelet transfusions given within 7 days of the routine weekly testings of the patient's serum for lymphocytotoxic antibodies (LCTAbs). Mean CCIs for HLA-matched platelet transfusions were calculated separately for the patients receiving them.
Results:
Thirty-one patients (24%) had or developed persistently positive LCTAbs (patient's serum reacted with > or = 3/10 panel lymphocytes); 22 (71%) of these patients had a mean CCI < 7.5 to random-donor platelet transfusions. In contrast, of the 97 patients with negative or transiently positive LCTAbs, only 25 (26%) had a mean CCI < 7.5. The overall incidence of platelet refractoriness (CCI < 7.5) was 37 percent. Patients with acute myelogenous leukemia had a significantly (p < 0.01) reduced incidence (17%) of low CCIs, with or without positive LCTAbs, as compared to patients with other malignant or nonmalignant disorders (41%). No difference in the incidence of LCTAbs or low CCIs was seen in patients undergoing allogeneic or autologous bone marrow transplant or receiving drug therapy only. Among the 24 patients who received HLA-matched platelets, only those with positive LCTAbs showed a significant improvement in CCIs over that achieved with random-donor platelet transfusions. Routine white cell reduction in red cell and platelet components with third-generation white cell filters was performed prior to transfusion in 73 of the patients. There was no significant difference between the incidence of LCTAbs and/or low CCIs in this group and that in the 55 children receiving unfiltered transfusions.
Conclusion:
Alloimmunization and platelet refractoriness occur in pediatric oncology and bone marrow transplant patients, but the incidence--particularly in children with acute myelogenous leukemia--appears to be low. The detection of LCTAbs predicts a poor response to random-donor platelet transfusion, but most such patients show improved CCIs with HLA-matched platelets. Routine use of white cell-reduction filters has thus far failed to eliminate alloimmunization in children requiring prolonged blood component support.