Human leukocyte antigen alloimmunization prevention mechanisms in blood transfusion

In many fields of clinical medicine and blood transfusion, the human leukocyte antigen (HLA) system is crucial. Alloimmunization happens as a result of an immune response to foreign antigens encountered during blood transfusion. This gives rise to alloantibodies against red blood cells (RBCs), HLA, or human platelet antigen (HPA). HLA alloimmunization following allogeneic transfusion was shown to be a result of contaminating white blood cells (WBCs) present in the product. It is a common complication of transfusion therapy that leads to difficulties in clinical intolerance and refractoriness to platelet transfusion during patient management. Single-donor platelets, prophylactic HLA matching, leukoreduction, and irradiation of cellular blood products are some of the mechanisms to prevent HLA alloimmunization during a blood transfusion. Now, the best approach to reduce the occurrence of primary HLA alloimmunization is the removal of WBCs from the blood by filtration.

First Indian initiative for preparation of low-titer group "O" single-donor platelets with platelet additive solution

BACKGROUND

Guidelines recommend ABO-identical platelet (PLT) transfusions. Hemolytic reactions after a minor ABO-incompatible PLT transfusion have escalated due to single-donor platelets (SDP) containing ABO-incompatible plasma. Avoiding such events by examining titers or performing plasma reduction is cumbersome. The introduction of platelet additive solutions (PAS) has enabled to reduce these reactions by avoiding passive transfer of isoagglutinin. Our aim was to study antibody titers (anti-A, anti-B) in "O" SDP by adding PAS at source and the quality parameters with reference to viability, morphology, and metabolism.

MATERIALS AND METHODS

Group "O" SDP (n = 50) were prepared on a standard cell separator. PAS in a ratio of 70:30 (PAS: plasma) was added at source under sterile conditions (study arm). The units were studied on day of collection (day 0) and day 4 and compared with SDP containing 100% plasma (control arm). A titer study was performed after PAS addition.

RESULTS

In the study group, the median antibody titers (anti-A, anti-B) reduced from 128 to16, post-PAS addition (P < 0.001). Morphology scores were superior in PAS platelet concentrates (P < 0.001). Metabolic parameters pO2 and pCO2 were similar in the two arms signifying good unit storage and stable oxygen consumption (P > 0.05). Lactate levels, glucose consumption rate, and lactate production rates were significantly low in study arm showing the advantage of PAS.

CONCLUSION

O group SDPs can be prepared with PAS and the beneficial effects were significant with respect to antibody titers. Quality parameters were well maintained. Availability of PAS units has benefitted patients.

Evaluation of bacterial inactivation in random donor platelets and single-donor apheresis platelets by the INTERCEPT blood system

BACKGROUND:

Blood transfusion of contaminated components is a potential source of sepsis by a wide range of known and unknown pathogens. Collection mechanism and storage conditions of platelets make them vulnerable for bacterial contamination. Several interventions aim to reduce the transfusion of contaminated platelet units; however, data suggest that contaminated platelet transfusion remains very common.

AIM:

A pathogen inactivation system, “INTERCEPT”, to inactivate bacteria in deliberately contaminated platelet units was implemented and evaluated.

MATERIALS AND METHODS:

Five single-donor platelets (SDP) and five random donor platelets (RDP) were prepared after prior consent of donors. Both SDP and RDP units were deliberately contaminated by stable stock ATCC Staphylococcus aureus and Escherichia coli, respectively, with a known concentration of stock culture. Control samples were taken from the infected units and bacterial concentrations were quantified. The units were treated for pathogen inactivation with the INTERCEPT (Cerus Corporation, Concord, CA) Blood system for platelets (Amotosalen/UVA), as per the manufacturer's instructions for use. Post illumination, test samples were analyzed for any bacterial growth.

RESULTS:

Post-illumination test samples did not result in any bacterial growth. A complete reduction of >6 log₁₀S. aureus in SDP units and >6 log₁₀Escherichia coli in RDP units was achieved.

CONCLUSION:

The INTERCEPT system has been shown to be very effective in our study for bacterial inactivation. Implementation of INTERCEPT may be used as a mitigation against any potential bacterial contamination in platelet components.