The second century of ABO: and now for something completely different

ABO-histo blood group incompatibility in hematopoietic stem cell and solid organ transplantation

In contrast to solid organ transplantation (SOT), ABO-histo blood group incompatibility is of minor importance for hematopoietic stem cell transplantation (HSCT). Patients receiving ABO-incompatible HSCT are at an increased risk for immune-mediated hematological complications including immediate and delayed hemolysis, late red blood cell engraftment and pure red cell aplasia, but seem not to have a worse overall survival or increased transplant-related mortality. This review gives an overview of the immunological mechanisms leading to complications associated with ABO-incompatible HSCT and describes approaches to prevent them. The current organ shortage in SOT stimulates the exploration of new strategies to expand the donor pool including ABO-incompatible SOT and xenotransplantation. Here, we discuss the hypothesis that ABO-incompatible transplantation may be viewed as a human in vivo model for the humoral immune mechanisms of antigen-mismatched transplantation. ABO-incompatible HSCT and SOT provide excellent possibilities to analyze graft accommodation and transplantation tolerance. Understanding the underlying mechanisms of graft survival in ABO-incompatible transplantation may facilitate new strategies to overcome the immunological barriers in SOT and xenotransplantation.

What would Karl Landsteiner do? The ABO blood group and stem cell transplantation

ABO blood group antigens, of great importance in transplantation and transfusion, are present on virtually all cells, as well as in soluble form in plasma and body fluids. Naturally occurring plasma IgM and IgG antibodies against these antigens are ubiquitous. Nonetheless, the ABO blood group system is widely ignored by many transfusion services, except for purposes of red cell transfusion. We implemented a policy of transfusing only ABO identical platelets and red cells in patients undergoing stem cell transplantation or treatment for hematologic malignancies. Major bleeding episodes have occurred in about 5% of patients undergoing induction therapy for acute leukemia as compared with 15-20% in the literature. Overall survival times appear to be superior to that in historical cohorts. In 2002-2004, treatment-related mortality at 100 days in our Blood and Marrow Transplant Unit was 0.7% for autologous transplants (n=148), 13% for sibling allogeneic transplants (n=110), and 24% (n=62) for matched unrelated allogeneic transplants, suggesting that our approach is safe. We speculate that more rigorous efforts on the part of transfusion services to provide ABO identical blood components, and to remove incompatible supernatant plasma, when necessary, might yield reduced morbidity and mortality in patients undergoing stem cell transplantation.

ABO Blood Group Barrier in Allogeneic Bone Marrow Transplantation Revisited

Reports have shown a worse outcome for donor-recipient pairs mismatched for ABO blood groups in bone marrow transplantation (BMT). These studies, however, included small and heterogeneous study populations, and not all considered bidirectional ABO incompatibility separately. Because the issue remains controversial, we analyzed the effect of ABO mismatch on the overall survival, transplant-related mortality, and occurrence of acute and chronic graft-versus-host disease (GVHD) in a large homogenous group of patients undergoing allogeneic BMT. A total of 3103 patients with early-stage leukemia who underwent transplantation between 1990 and 1998 with bone marrow from an HLA-identical sibling and who were reported to the Center for International Blood and Marrow Transplant Research were studied. The median follow-up was 54 months. A total of 2108 (67.9%) donor-recipient pairs were ABO identical, 451 (14.5%) had a minor mismatch, 430 (13.9%) had a major mismatch, and 114 (3.7%) had a bidirectional ABO mismatch. The groups did not differ significantly in patient or donor characteristics except for more female-to-male sex mismatch in the bidirectional ABO mismatch group (P = .017). In multivariate models of overall survival, transplant-related mortality, and grade II to IV acute GVHD, there were no significant differences among the 4 groups. Bidirectional ABO mismatch was associated with a significantly higher risk of grade III or IV acute GVHD (hazard ratio, 1.869; 95% confidence interval, 1.192-2.93; P = .006). Patients with major ABO mismatch received red blood cell transfusions (P = .001) for a longer timer after transplantation and had a slightly slower neutrophil recovery (P < .001). There was no evidence of a substantial effect of ABO blood group incompatibility on the outcome of conventional BMT among patients with leukemia.

Universal fresh-frozen plasma (Uniplas): an exploratory study in adult patients undergoing elective liver resection

BACKGROUND AND OBJECTIVES

The compatibility of an ABO blood group independently applicable plasma, Uniplas, was explored in liver resection because patients undergoing liver resection frequently require the transfusion of plasma to compensate for blood loss and/or clotting factors.

MATERIALS AND METHODS

One-hundred and twenty two patients undergoing elective liver resection were enrolled; 81 patients required plasma transfusion, while 41 did not. Of those in need of plasma, 58 were blood group A, B or AB, and 23 were blood group O. Patients were monitored up to day 7 postoperatively for signs of haemolysis and haemostasis, and viral markers were assessed at baseline and 3 weeks postoperatively.

RESULTS

Uniplas transfusions of up to 50.7 ml/kg body weight were given per treatment episode, without signs of haemolysis caused by transfusion. A total of 94/99 patients (95%) were negative in the direct antiglobulin test throughout the study. Two patients, one transfused with Uniplas, the other not, had a positive direct antiglobulin test result at baseline, while three of 64 patients transfused with Uniplas demonstrated a change from having negative to intermittently positive direct antiglobulin test results without concurrent signs of haemolysis. International normalized ratio, activated partial thromboplastin time and protein C levels were maintained by transfusion of plasma (>/= 20 ml/kg body weight). No patient underwent seroconversion for human immunodeficiency virus, hepatitis B virus or hepatitis C virus. Positivity for hepatitis A virus (HAV) immunoglobulin G (IgG) in 11 patients from the Uniplas group (who tested HAV immunoglobulin M negative), together with an apparent seroconversion for parvovirus B19 seen in two patients who received Uniplas, indicated passively transferred IgG antibodies.

CONCLUSIONS

No haemolysis was observed as a result of Uniplas transfusions up to 50.7 ml/kg body weight per treatment episode in patients undergoing liver resection. Moreover, transfusion (>/= 20 ml/kg body weight of Uniplas) maintained acceptable levels of international normalized ratio, activated partial thromboplastin time and protein C.

Optimizing platelet transfusion therapy

Platelet transfusions are widely used. Prophylactic transfusions are employed in severely thrombocytopenic patients without evidence of bleeding, but no randomized trial data prove the safety or efficacy of this approach. Randomized trials have demonstrated the equivalence of transfusion triggers of 10,000 and 20,000/microl for prophylactic transfusions. The former threshold is potentially safer for the patient, conservative of donor resources and leads to lower costs, with perhaps a slightly greater risk of minor hemorrhage. Randomized trials have demonstrated the equivalence of pheresis or whole blood-derived platelet transfusions. The former present a lower risk for infectious agents, and the latter are less expensive and a more efficient use of limited donor resources. Randomized trials prove that leukoreduced and ABO identical platelet transfusions reduce the risks of HLA alloimmunization and platelet transfusion refractoriness (both leukoreduction and ABO matching), transfusion reactions (leukoreduction) and CMV transmission (leukoreduction). Leukoreduction and ABO matching of platelet transfusions also have been associated in preliminary observational studies with reduced morbidity and mortality in surgical patients and reduced infections in patients with leukemia. These results require further investigation. Future challenges include (1) determining the best approach to bacterial contamination of platelets, whether by detection methods or pathogen inactivation and (2) determining the threshold for prophylactic platelet transfusions in thrombocytopenic patients undergoing surgery or invasive procedures.

Universal fresh frozen plasma (Uniplas): a safe product in open-heart surgery

OBJECTIVE

To test the tolerability and safety of the universal plasma Uniplas [solvent/detergent (SD)-treated plasma], infused regardless of the patient's blood group.

DESIGN

Prospective, parallel group, controlled and observer-blinded study, randomized with respect to patients requiring plasma transfusion.

SETTING

Cardiothoracic operating room and ICU in a university hospital.

PATIENTS

Eighty-four patients undergoing open-heart surgery comparing three parallel treatment groups and one control group.

INTERVENTIONS

The Uniplas treatment group was subdivided into patients with blood group A, B or AB, and group O. The treatment group receiving Octaplas of type AB, was not subdivided. Patients who did not require any plasma transfusion served as control.

MEASUREMENTS

Complement activation (C3bc, TCC), direct antiglobulin test (DAT) and other immunohaematological tests, tests for haemolysis, and relevant clinical observations during treatment phase. Blood samples were collected again after 6 months for evaluation of viral safety.

RESULTS

Of the 84 patients, 29 served as control group. Uniplas was transfused in 36 of the patients (1-23 units). Octaplas was transfused in 19 patients (1-11 units). During the study no clinical adverse events related to plasma transfusion were observed. The degree of complement activation C3bc and TCC, a recommended test for biocompatibility, did not show any increased activation after Uniplas or Octaplas transfusion. No haemolytic reactions, positive DAT-tests or viral transmissions were observed after Uniplas transfusion.

CONCLUSION

In open-heart surgery, Uniplas, which can be transfused regardless of a patient's blood group, was well-tolerated and gave no adverse drug reactions.

Consequences of ABO incompatibility in allogeneic hematopoietic stem cell transplantation

Aside from causing hemolytic reactions the ABO blood group system does not have an impact on outcome after allogeneic bone marrow or peripheral blood stem cell transplantation (SCT). However, only a few studies have addressed the effect of ABO incompatibility on the incidence of GVHD, time to engraftment, relapse and survival. Therefore, we performed a retrospective two-center analysis of 562 consecutive patients receiving allogeneic SCT, including 361 ABO-identical, 98 minor, 86 major and 17 bidirectional ABO-incompatible SCT. In multivariate analysis adjusted for potential confounders survival was significantly associated with ABO incompatibility (P = 0.006). Compared to ABO-identical SCT, bidirectional ABO incompatibility increased the risk significantly (RR, 2.8; 95% CI, 1.5-5.1; P = 0.0009), whereas survival of patients with minor (RR, 1.2; 95% CI, 0.9-1.7; P = 0.27), or major ABO-incompatible SCT (RR, 1.3; 95% CI, 0.9-1.8; P= 0.18) was not significantly different. RBC engraftment was delayed in major ABO-incompatible SCT (RR, 0.66; 95% CI, 0.51-0.85; P = 0.001). The incidence of acute GVHD (grade I-IV) was higher in minor ABO-incompatible SCT as compared to ABO identity (RR, 2.8; 95% CI, 1.3-5.9, P = 0.009). This difference was limited to mild GVHD; in moderate-to-severe GVHD (grade II-IV) no significant difference was found among the groups (P = 0.53). The relapse rate was not influenced by ABO incompatibility (P = 0.78). In conclusion, these results suggest that ABO incompatibility represents a risk factor not only for post-transplant hemolysis, but also for survival and the rate of mild GVHD after allogeneic SCT.

Rational use of blood products

Blood product transfusions can be life saving and must be considered in the supportive care of children of any age with underlying oncological or haematological problems, as well as after major surgery or after serious trauma. Paediatric transfusions are particularly challenging because life-long effects of transfusion complications are more durable and serious in children than in adults, in whom the median age at transfusion is >70 years (Tynell E, Norda R, Shanwell A, Björkman A. Long-term survival in transfusion recipients in Sweden, 1993. Transfusion 2001, 41, 251-255). While the general indications for transfusions in paediatric patients are similar to adults, the threshold, volumes and infusion rates for transfusions vary with age. In this Update, we discuss current blood products, then suggest transfusion "triggers" in major surgery and haematological and oncologic practice. Finally, future developments and new possibilities are considered.

Association of ABO-mismatched platelet transfusions with morbidity and mortality in cardiac surgery

BACKGROUND

The transfusion of ABO-mismatched platelets has been associated with increased morbidity and mortality during induction therapy for acute leukemia and allogeneic progenitor cell transplantation.

STUDY DESIGN AND METHODS

Reported here is a cohort study of 153 patients undergoing primary coronary artery bypass graft or coronary valve replacement surgery by two surgeons in one institution during 1997 and 1998. All statistics employed nonparametric two-sided tests (Mann-Whitney; Fisher's exact test).

RESULTS

Patients receiving at least one ABO-mismatched pool of platelets had a significantly longer hospital stay, more days of fever, greater total hospital charges, and more RBC transfusions. Mortality, hours in the intensive care unit, days on antibiotics, and numbers of platelet transfusions were also greater in recipients of ABO-mismatched platelets, but these differences were of less statistical significance. When the analysis was restricted to the 139 patients who received no more than two pools of platelets, the trends for increased morbidity and mortality (8.6% vs. 1.9%; p = 0.10) in recipients of ABO-mismatched platelets persisted. The number of RBC transfusions required in this latter cohort was 50 percent greater (mean, 6.1 vs. 9.2; p = 0.02), despite the fact that the number of platelet transfusions given was similar (mean, 1.2 vs. 1.3 pools; p = 0.22).

CONCLUSIONS

ABO-mismatched platelet transfusions are associated with unfavorable outcomes in cardiac surgery, a relationship that remains unexplained. As this association has been found in three cohort studies in various clinical settings, further investigation of this association is warranted.

Graft-versus-host disease and survival after ABO-incompatible allogeneic bone marrow transplantation: a single-centre experience

The effect of ABO-incompatibility on graft versus host disease (GVHD) and survival was evaluated in 173 consecutive patients receiving allogeneic bone marrow transplantation (BMT). Thirty-four percent of the patients developed GVHD and univariate analysis suggested a higher incidence of GVHD in minor ABO-incompatibility than in ABO-identity (14/30, 47% versus 37/112, 33%; P = 0.02). However, using logistic regression adjusted for potential confounders, the GVHD risk did not differ significantly. During a mean follow-up time of 59 months, the mortality was 37% and survival was significantly dependent on ABO-compatibility (P = 0.004). In particular, patients with bidirectional ABO-incompatibility had an excess mortality rate (RR, 7.6; 95% CI, 2.5-23.2; P = 0.0004). Taken together, these results suggest that ABO-incompatibility may represent a risk factor in allogeneic BMT.