A retrospective observational study to estimate the risk of HLA alloimmunization with blood transfusion: Can the risk be reduced by leucodepletion?

BACKGROUND: In this retrospective study, our aim was to find the effect of leucodepleted (LD) blood transfusions on the formation of anti-HLA-antibodies when compared to non-leucodepleted (non-LD) transfusions using Luminex-based method. METHODS: In this study, Luminex single antigen bead assay (L-SAB) and HLA typing were performed on 310 patients. Test positivity rates (as MFI - Mean florescence intensity) were analyzed according to the different sensitization events and gender. RESULTS: Of the 310 patients included in the study, 58.06% (180) patients were male and 41.93% (130) were female. The average age of the patients was 42.86 (±12.37) years. In this study, test positivity rates were significantly lower in the patients who received LD RBC units than in those who received non-LD RBC units (28.43% = 29 of 102 Vs 55.22% = 74 of 134, p < 0.05). In our study, transfusion combined with a history of pregnancy had higher number of significant HLA antibodies compared to cases where transfusion was the only sensitization event (81.81% = 18/22 Vs 39.71% = 85/214, p < 0.05). In addition, anti-HLA-antibodies-MFI were significantly (p < 0.01) higher in non-LD patients compared to LD patients. CONCLUSION: Patients who received LD RBC units had a significantly lower rate of transfusion-associated alloimmunization compared to those who received non-LD RBC units. Multiparous women had a high risk for transfusion-related alloimmunization compared to both nulliparous women and male patient. Furthermore, class I-anti-HLA-antibodies (HLA-B and HLA-A + B) were significantly associated with pregnancy sensitization and/or blood transfusion as a single sensitization.

Detection of donor-specific HLA antibodies: A retrospective observation in 350 renal transplant cases.

BACKGROUND: The main objective of this study was to determine the results of the cell-based assay (CDC-XM and FC-XM), and correlate with the results of solid phase assay (L-SAB). METHODS: In this retrospective study, 350 prospective renal transplant recipients were tested for the presence of HLA antibodies by CDC-XM, FC-XM and L-SAB screening with their corresponding donor. RESULTS: T-cell-FC-XM showed a sensitivity of 71.43% and a specificity of 91.50% for detecting class I L-SAB (+), while B-cell-FCXM showed a sensitivity of 94.94% and a specificity of 61.99% for detecting class II L-SAB (+). On the other hand, T-CDC-XM showed a sensitivity of 32.14% and a specificity of 98.64% for detecting class I L-SAB (+), while B-CDC-XM showed a sensitivity of 44.30% and a specificity of 94.83% for detecting class II L-SAB (+). In this study, the results indicated that DSA class I MFI value of 2845 and above significantly (p ≤0.001) correlated with T-cell-FC-XM positivity, while MFI value of 4585 and above (p ≤0.001) showed strong predictive accuracy of a positive T-cell-CDC-XM. However, DSA class II MFI cut-off of 1988 and above significantly (p ≤0.001) correlated with B-cell-FC-XM positivity, while MFI value of 5986 and above (p ≤0.001) showed strong predictive accuracy of a positive B-cell-CDC-XM. CONCLUSIONS: Our study showed that CDC-XM has poor sensitivity, while FC-XM has poor specificity to detect DSA. L-SAB has good correlation with T-cell-FC-XM (p < 0.0001) but not with B-cell-FC-XM (P = 0.31). DSA strength >2845 and > 1988 significantly correlated with T-cell-FC-XM positivity and B-cell-FC-XM positivity, respectively. While, a MFI value of >4585 and > 5986 significantly correlated with T-cell-CDC-XM positivity and B-cell-CDC-XM positivity, respectively. These MFI cut-off values could serve as a surrogate marker for CDC-XM and FC-XM tests and may help in resolving the limitations of cell-based techniques. In conclusion, we found that L-SAB is more sensitive and specific than CDC-XM and FC-XM and therefore may be used as a test of choice.