Solvent detergent treated pooled plasma and reduction of allergic transfusion reactions

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) patients have increased risk for allergic transfusion reactions (ATR) due to the number of plasma products they require. This study evaluated the efficacy of solvent detergent treated plasma (S/D treated plasma) to reduce ATRs.

STUDY DESIGN AND METHODS

All TTP patients who presented from April 2014 to February 2015 and experienced a moderate-severe ATR to untreated plasma with TPE were switched to S/D treated plasma (Octaplas) for their remaining procedures and included in the study. Patient records were retrospectively reviewed.

RESULTS

The overall ATR rate per procedure decreased from 35.0% (95% CI = 15.4%-59.2%) with untreated plasma to 1.4% ([1/73] 95% CI = 0.0%-7.4%) with S/D treated plasma. The moderate-severe ATR rate decreased from 20.0% ([4/20] 95% CI = 5.7%-43.7%) with untreated plasma to 0.0% ([0/73] 95% CI = 0.0%-4.9%) with S/D treated plasma. The overall ATR rate per plasma unit decreased from 2.6% (95%CI = 1.0%-5.1%) with untreated plasma to 0.1% (95% CI = 0.0%-0.4%) with S/D treated plasma. No patients experienced VTE while receiving untreated plasma. Four patients experienced VTE events while receiving S/D treated plasma. All patients who experienced a VTE had additional risk factors for VTE.

CONCLUSION

S/D plasma has promise as an effective product to reduce the risk of ATRs in TTP patients. Given the high risk of ATR in TTP patients, consideration of S/D plasma instead of untreated plasma for TPE in these patients may be warranted, especially for patients with a history of moderate to severe ATR. More extensive studies are needed to confirm these findings.

Prevalence of clinically significant red blood cell alloantibodies in pregnant women at a large tertiary-care facility

More than 50 red blood cell (RBC) alloantibodies are known to cause hemolytic disease of the fetus and newborn (HDFN).Although Rh immune globulin (RhiG) prophylaxis has significantly reduced the incidence of pregnancies complicated by anti-D, the need to detect and monitor maternal allo antibodies capable of causing HDFN is still a concern. The prevalence and specificity of these alloantibodies were determined. In this retrospective study, the prevalence and specificities of unexpected RBC alloantibodies known to cause HDFN in pregnant women at a tertiary-care facility during a 5-year period were compiled and analyzed. Patient selection was carried out by computerized search of patient data based on an obstetric location and the presence or history of RBC antibody between January 1, 2007,and December 31, 2011. The information was organized by ABO and D status of the patient, antibody specificity, and transfusion needs. Of the 8894 obstetric patients identified during the 5-year period, 264 (3.0%) had one or more unexpected RBC antibodies.Of these 264 women, 107 (40.5%), or 1.2 percent overall, had an alloantibody known to cause HDFN, with a total of 15 different alloantibodies identified. The most common alloantibody found was anti-E (n = 33), followed by anti-M (n = 26) and anti-D (n= 20). In pregnancies of D- women, the most common clinically significant antibodies found were anti-D (n = 20), anti-C (n = 11),and anti-E (n = 2). In pregnancies of D+ women, the most common antibodies were anti-E (n = 31), anti-M (n = 25), and anti-K (n= 16). A total of eight pregnancies with alloantibodies required intrauterine transfusions with the specificities of anti-D; anti-D,-C(n = 2); anti-D,-C,-E; anti-D,-C,-K; anti-D,-C,-Jkb; anti-D,-S; and anti-E,-c. At a large academic tertiary-care center, approximately 1 in 83 obstetric patients had one or more RBC alloantibodies capable of causing HDFN. Anti-E, -M, and -D were the most frequent specificities, respectively.

Universal leukoreduction decreases the incidence of febrile nonhemolytic transfusion reactions to RBCs

BACKGROUND

Febrile nonhemolytic transfusion reactions (FNHTR) is a relatively common complication associated with allogeneic transfusion. Because WBCs have been implicated in the mechanism of FNHTRs, it has been proposed that the transfusion of leukoreduced RBCs should be associated with a decreased incidence of FNHTRs. These reactions are generally not life threatening, but they are expensive in their management, evaluation, and associated blood-product wastage. Over the past several years, the proportion of leukoreduced RBCs has increased at Johns Hopkins Hospital in an effort to move toward complete leuko-reduction. A retrospective analysis is reported here of FNHTRs in RBC recipients as the inventory increased in percentage of leukoreduced RBC units.

STUDY DESIGN AND METHODS

Between July 1994 and December 2001, all transfusion reactions (TRs) associated with the transfusion of allogeneic RBCs were retrospectively analyzed. Both computerized data and individual TR reports were reviewed. Patients who had both allergic and febrile features were included as part of both categories. TRs were reported as a percentage of total units transfused. Two time periods were selected for direct comparison. July to December 1994 represents the time period before the initiation of an increase in leuko-reduction. July to December 2001 represents a time period when almost complete leukoreduction (99.5%) had been achieved. The TR data were compared between these two time periods, comparing a time before leuko-reduction to a time period after leukoreduction had been achieved. The trends in TRs over the entire 7.5-year period of July 1994 to December 2001 were also assessed.

RESULTS

In the initial period before the initiative to move toward leukoreduction, 96 percent of our RBC inventory was non-leukoreduced. In the study period after leukoreduction, 99.5 percent of our RBC inventory was leukoreduced. When comparing these two time periods, the incidence of FNHTRs decreased from 0.37 percent to 0.19 percent (p = 0.0008). The trend over the entire 7.5-year study period confirms the decrease in FNHTRs as the percentage of leukoreduced RBCs increased. The incidence of allergic TRs has remained unchanged over this time period.

CONCLUSIONS

As our institution has increased its inventory of leukoreduced RBCs to approximately 100 percent, selective leukoreduced protocols have been discontinued. The incidence of FNHTRs has decreased significantly and the rate of allergic reactions has essentially remained unchanged. Leukoreduction is effective in decreasing FNHTRs associated with the transfusion of allogeneic RBCs.

The differentiation of delayed serologic and delayed hemolytic transfusion reactions: incidence, long-term serologic findings, and clinical significance

Delayed serologic transfusion reactions (DSTRs) and delayed hemolytic transfusion reactions (DHTRs) were studied in a large tertiary-care hospital. A DSTR was defined by the posttransfusion finding of a positive direct antiglobulin test (DAT) and a newly developed alloantibody specificity. A DHTR was defined as a DSTR case that showed clinical and/or laboratory evidence of hemolysis. Thirty-four cases of DSTR, 70 percent of which were due to anti-E and/or -Jka, were documented prospectively over a 20-month period. Retrospective review of the medical records found clinical evidence of hemolysis in only 6 (18%) of the 34. Thus, the incidence of DSTR was 1 (0.66%) of 151 recipients with posttransfusion samples available for testing, whereas the incidence of DHTR was only 1 (0.12%) of 854 patients tested. Fifteen of the 34 patients were followed for up to 174 days after reaction. Twelve of the 15 still demonstrated a positive DAT with anti-IgG only. Eluate studies indicated that the persistence of a positive DAT after DSTR or DHTR may involve several immunologic mechanisms, including the development of posttransfusion autoantibodies. This study indicates 1) that DSTRs are a frequent finding in multiply transfused patients, although most cases are benign and fail to meet rigid criteria for DHTR, and 2) that the persistence of a positive DAT after DSTR or DHTR is common.