HLA class I antibody distribution and cross-matching strategies in immune platelet transfusion refractory patients: a retrospective cohort study.

BACKGROUND: This study aimed to investigate the distribution characteristics and clinical significance of human leukocyte antigen class I antibodies in patients with immune-mediated platelet transfusion refractoriness (PTR) in this region, and to evaluate the clinical utility of local serological cross-matching strategies for improving platelet transfusion efficacy. METHODS: A retrospective cohort study was conducted involving 229 patients who underwent platelet antibody screening. Platelet antibody screening and cross-matching were performed using solid-phase agglutination assays. Human leukocyte antigens (HLA) antibodies were detected via Luminex liquid bead array technology to obtain mean fluorescence intensity (MFI), and HLA class I antibody specificity was identified using Luminex single-antigen beads. The corrected count increment (CCI) was employed as the primary efficacy evaluation metric to compare the clinical outcomes among different transfusion strategy groups. RESULTS: Subgroup analysis revealed: in the random transfusion group, the PTR incidence was 26.92% (7/26), with a median 24 h CCI of 7.35 (3.03, 10.78); the cross-incompatible group showed a significantly higher PTR incidence of 80.0% (4/5), with a median 24 h CCI of 0.00 (-2.54, 9.39); while the cross-compatible group had a PTR incidence of 22.72% (5/22), with a median 24 h CCI of 8.11 (3.02, 12.30). The platelet antibody positivity rate was 20.96% (48/229), with 62.5% (30/48) originating from hematologic malignancies. Among these, HLA antibody positivity reached 75.61% (31/41), with HLA class I antibodies accounting for 93.55% (29/31). HLA-B locus antibodies were the most common. The maximum MFI of HLA class I antibodies was negatively correlated with the 24 h CCI (r s = -0.368, p = 0.032). The area under the receiver operating characteristic was 0.825 (95% CI: 0.600-0.954), and the optimal cut-off value was MFI = 1,525.6 (sensitivity 71.50%, specificity 85.50%). CONCLUSION: This study analyzed the distribution characteristics of HLA class I antibodies in suspected or highly suggestive immune-mediated PTR patients and found that the highest MFI value of HLA class I antibodies can serve as an indicator of the maximum observed HLA antibody reactivity. Based on a serological crossmatch transfusion strategy, this approach provides a feasible implementable platelet transfusion protocol for primary hospitals in southwestern China that lack HLA genotyping capabilities.