Background/Case Studies: Immune-mediated platelet refractoriness primarily occurs due to the presence of HLA antibodies. HLA-compatible platelets, while often effective in increasing post-transfusion increments, are not always available for heavily sensitizedpatients. In such cases, the transfusion of partially matched platelets (i.e., compatible with some but not all donor-specific antibodies) may be attempted. In this study, we reviewed corrected count increments (CCI) in patients who received partially HLA matched platelets and compared them to the increments observed after the receipt of fully compatible or random donor platelets.
Study
Design/Methods: Adults with a history of refractory thrombocytopenia associated with a calculated PRA > 20% from period June to October 2023, who had received at least one partially HLA-compatible platelet transfusion were included. Patients who received platelets from a random donor during this period with a CCI > 10 were excluded from further analysis, as they were no longer considered refractory to platelets. Partially-HLA-matched platelets were defined as those in which incompatibility for at least one donor-specific antibody (DSA) with a mean fluorescence intensity < 3000 by Luminex® flow bead testing was permitted due to difficulty sourcing fully compatible products. The primary outcome of interest was the mean difference in CCI following the transfusion of HLA-compatible, partially-HLA compatible and random platelets, as determined by ANOVA. In a secondary analysis, a multivariable regression was performed to determine the correlation between CCI and the presence of ABO compatibility, the MFI of any non-matched DSAs, the age of both the patient and platelet product, patient diagnosis and spleen size.
Results/Findings: Five patients who had received a total of 69 platelet transfusions (Figure 1) were included in the analysis. No difference in average post-transfusion CCI was observed when comparing HLA compatible and partially HLA-matched platelets (10.96 ± 9.77 and 10.48±7.80, p = 0.84).However, both produced significantly higher increments than what was observed following the transfusion of random platelets (1.34 ± 2.88, p < 0.01). In the multivariable regression model, the receipt of either fully- or partially-HLA-matched platelets (p < 0.05) and spleen size (p < 0.01) were statistically significant predictors of post-transfusion increment, while ABO mismatch, patient age, product age, and patient diagnosis were not statistically significant. Conclusions: Our case series suggests that transfusing partially HLA-compatible platelets achieved a similar post-transfusion increment as fully-HLA-compatible platelets and may be a reasonable option when fully HLA-compatible platelets are not available. Future research will seek to validate these observations by performing larger, prospective observational studies.
