Platelet transfusion refractoriness caused by a mismatch in HLA-C antigens.

BACKGROUND

HLA-C antigens have been thought to be of little significance in determining the efficacy of platelet transfusions. However, six alloimmunized patients were encountered who were refractory to platelet transfusions because of anti-HLA-Cw3, -Cw3, -Cw7, or -Cw8.

STUDY DESIGN AND

METHODS

Between 1995 and the present, 88 patients with hematologic malignancies became refractory to random-donor platelet transfusions due to HLA antibodies. HLA-A- and HLA-B-compatible platelet transfusions were successful in boosting platelet levels with 82 of the patients. This study concerns the remaining six HLA-immunized patients who were refractory to HLA-A- and HLA-B-compatible platelet transfusions. The response to the platelet transfusions was assessed by calculating both 1- and 24-hour posttransfusion CCIs for each transfusion.

RESULTS

The average CCI(1 hour) and CCI(24 hours) in all patients were 20.0 and 12.8 for HLA-A-, HLA-B-, and HLA-C-compatible transfusions and were 1.4 and 1.2 for HLA-A- and HLA-B-compatible but HLA-C-incompatible transfusions, respectively (p < 0.001).

CONCLUSION

These findings clearly indicate that matching of the HLA-C antigens is also required in some alloimmunized patients to obtain the effectiveness of platelet transfusions.