Transfusion‐induced platelet antibodies and regulatory T cells in multiply transfused patients

BACKGROUND: Platelet transfusion refractoriness (PTR) remains a difficult problem in patients requiring long‐term platelet supportive care. However, there are little data on the frequency of platelet antibodies in multiply transfused Chinese patients. Moreover, the relationship between peripheral regulatory T cells (Tregs) and PTR remains unclear. METHODS: We retrospectively studied the frequency of alloimmunization against platelet antigens in patients receiving multiple transfusions between 2013 and 2017. Monoclonal antibody solid‐phase platelet antibody test (MASPAT) kits were used to screen for platelet antibodies before each platelet transfusion. Peripheral Tregs and CD4(+)CD25(+)CD127(−) T cells were detected by flow cytometry, while transforming growth factor‐beta (TGF‐β) and interleukin (IL)‐17 cytokines were detected by enzyme‐linked immunosorbent assay. RESULTS: A total of 399 patients who met the inclusion criteria were enrolled for the analysis of platelet antibodies and refractoriness. Among these patients, 10 (2.5%) were positive for platelet antibodies before transfusion and 47 (11.8%) became antibody‐positive during the study period. The number of alloimmunized patients was significantly higher in patients with hematological disease as compared with other disease groups (p < 0.05). Refractoriness and alloimmunization occurred in 77 (19.3%) and 22 (28.6%) patients, respectively. There were no significant differences in CD4(+), CD8(+), and CD4(+)CD25(+)CD127(−) T cell numbers and plasma levels of TGF‐β1 and IL‐17 between patients with PTR and the control group. CONCLUSIONS: Refractoriness was common in patients undergoing multiple platelet transfusions (19.3%), with alloimmunization observed in 28.6% of patients. However, Tregs in peripheral blood may not play a key role in PTR.