Occult alloimmunization to the D antigen (RhD) related to graft versus host disease and its treatment.

Alloimmunization to red blood cell (RBC) antigens post-allogeneic stem cell transplantation (allo-SCT) appears to be quite rare. The D antigen (RhD) is considered the most immunogenic RBC antigen with possibly a third of RhD-negative individuals exposed to RhD-positive RBC transfusions becoming alloimmunized. Though variable, most are detectable within a year of exposure, and the median time between exposure and detection is estimated to be about a month. We report the detection of anti-D in an allogeneic bone marrow transplant (allo-BMT) recipient about five years following last exposure to RhD-positive RBC.

Evaluation of clinical coding data to determine causes of critical bleeding in patients receiving massive transfusion: a bi-national, multicentre, cross-sectional study.

OBJECTIVES: To evaluate the use of routinely collected data to determine the cause(s) of critical bleeding in patients who receive massive transfusion (MT). BACKGROUND: Routinely collected data are increasingly being used to describe and evaluate transfusion practice. MATERIALS/METHODS: Chart reviews were undertaken on 10 randomly selected MT patients at 48 hospitals across Australia and New Zealand to determine the cause(s) of critical bleeding. Diagnosis-related group (DRG) and International Classification of Diseases (ICD) codes were extracted separately and used to assign each patient a cause of critical bleeding. These were compared against chart review using percentage agreement and kappa statistics. RESULTS: A total of 427 MT patients were included with complete ICD and DRG data for 427 (100%) and 396 (93%), respectively. Good overall agreement was found between chart review and ICD codes (78·3%; κ = 0·74, 95% CI 0·70-0·79) and only fair overall agreement with DRG (51%; κ = 0·45, 95% CI 0·40-0·50). Both ICD and DRG were sensitive and accurate for classifying obstetric haemorrhage patients (98% sensitivity and κ > 0·94). However, compared with the ICD algorithm, DRGs were less sensitive and accurate in classifying bleeding as a result of gastrointestinal haemorrhage (74% vs 8%; κ = 0·75 vs 0·1), trauma (92% vs 62%; κ = 0·78 vs 0·67), cardiac (80% vs 57%; κ = 0·79 vs 0·60) and vascular surgery (64% vs 56%; κ = 0·69 vs 0·65). CONCLUSION: Algorithms using ICD codes can determine the cause of critical bleeding in patients requiring MT with good to excellent agreement with clinical history. DRG are less suitable to determine critical bleeding causes.

Transfusion-associated dyspnea--shadow or substance?

New Zealand Blood Service Haemovigilance uses International Society of Blood Transfusion/International Haemovigilance Network definitions to categorize transfusion reactions (TR). Transfusion-associated dyspnoea (TAD) is a category for TR with respiratory features (TRRF) that do not fit definitive entities. TRRF, including TAD, are clinically significant. TR classified as TAD were reviewed. We found that many TAD may have been transfusion-associated circulatory overload. Better information in TR reports and refining TR diagnostic criteria may result in less misclassification of TRRF. TAD may represent mild, atypical or overlap entities, and there may be a residuum of cases with currently unexplained pathophysiology.

Induction of immune tolerance to RBC, platelet, and neutrophil antigens and IgA.

Antibodies to red blood cell (RBC), platelet, and neutrophil antigens, and IgA may cause serious clinical problems. With a few exceptions, preventing these conditions is a matter of limiting exposure to the foreign antigen while treatment consists of managing the consequences. Might immune tolerance induction (ITI) be possible and beneficial in these situations? Neonatal exposure to antigens is known to induce central tolerance. However central tolerance may not be absolute. Factors that determine whether an antibody will be produced in response to an antigen are not well understood but include the appropriate expression of major histocompatibility complex-class II and/or co-stimulatory molecules on dendritic cells, the presence or absence of adjuvants and whether or not the antigen is presented together with agonists for the toll-like receptor. Modifying these may prevent alloimmunization. Peripheral tolerance, in sensitized individuals, as routinely used in patients with allergic/anaphylactic reactions, those with haemophilia A or B with inhibitors and acquired haemophilia, may also be possible. Briefly, monitored, graded, increasing exposure to the antigen of interest with or without additional immunosuppression is used. Neither central nor peripheral ITI has been tried or suggested for individuals sensitizable or sensitised to RBC, platelet, and neutrophil antigens, or IgA. Theoretically, this is possible and may be of benefit.

Red blood cell phenotyping after transfusion: an in vitro model.

Recipients red blood cell (RBC) phenotyping using serologic techniques, within 3 months of a transfusion, is considered unreliable. We conducted in vitro experiments to determine how long recipients RBC phenotyping results would be compromised. In vitro models were created to mimic in vivo posttransfusion ratios of "transfused" RBCs with either a single or a double dose of an antigen at 10-day intervals from day 0 to day 90 in hypothetical recipients with varying weights and hematocrits (Hct) receiving varying numbers of RBC units. In general, a reliable recipient RBC phenotype was possible earlier after transfusion in larger recipients, those with higher Hct, and those transfused with fewer RBC unit and if the transfused units had the antigen of interest in single, rather than double, dose. We believe that a reliable RBC phenotype, using routine serologic techniques, can often be obtained well before 3 months after transfusion. Similar studies with other donors, antigens, antisera, and methods and in actual patients will be useful.

Difficult venepuncture--it was all in the head!

AIM: To emphasise the importance of careful observations and demonstrate that significant conditions may, on occasion, be detected during blood donation. BACKGROUND: Venepunctures, the bread and butter of blood donor services, can be difficult procedures. We describe an unusual presentation of a relatively rare disease detected during routine blood donations because of difficult venepunctures. METHODS: Case report. RESULTS: A growth hormone-secreting pituitary adenoma was diagnosed, and successfully treated, following the initial observation of hard-to-puncture skin during blood donations. CONCLUSIONS: Seemingly trivial abnormalities may prove clinically important. One presentation of acromegaly is hard-to-puncture skin.

Demographic, laboratory, and operational variables that influence short- and long-term plateletpheresis yields.

We studied the demographic, laboratory, and operational parameters that might influence individual, as well as average, plateletpheresis yields. Multivariate linear regression analyses showed that 25.4% and 11.6% of variability, among males and females, respectively, in individual yields was explained by the platelet count prior to that donation and 55% of the variation in mean platelet yields (PYs) was explained by the pre-first donation platelet count, the first donation PY and the body mass index (BMI). Logistic regression analysis showed that donors with first donation PYs higher, compared to those with lower yields, than the median of all mean PYs were more likely to be relatively high platelet yielders over the long term. A statistically significant, although clinically insignificant, decline in predonation platelet counts is seen in all donors regardless of the total number of donations or interdonation interval. Donors with high pre-first donation platelet counts, first donation yields, and BMI are likely to be consistent good platelet yielders.

Maternal IgM anti-D, borderline foetal Doppler middle cerebral artery velocities and absent neonatal haemolysis.

Anti-D was detected for the first time at 36 weeks gestation in a group A RhD-negative primigravida without prior sensitizing events or anti-D administration. Simultaneously, foetal ultrasound showed middle cerebral artery maximum velocity (MCA V(max)) at the 95th centile but no hydrops. Labour was induced at 37 weeks. Although neonatal anaemia was anticipated, the baby, who was group O RhD-positive, was born with a normal haemoglobin and negative direct antiglobulin test and antibody screen. Retrospectively, the maternal anti-D proved to be exclusively immunoglobulin M (IgM), which does not cross the placenta. Foetal Doppler MCA V(max) measurements can give false positive results especially late in the third trimester. Thus, antibody class, especially in first pregnancies without prior sensitizing events, and the timing of foetal Doppler MCA velocity measurements should be considered when evaluating the likelihood and severity of haemolytic disease of the foetus and newborn.

Cytomegalovirus seroprevalence and 'cytomegalovirus-safe' seropositive blood donors.

Cytomegalovirus (CMV) seroprevalence was determined in 9343 first-time New Zealand blood donors between 2003 and 2006. Of 39 960 current seropositive donors the proportion testing seropositive more than 12 months previously was calculated. Overall, seroprevalence declined from 66.1% [95% confidence interval (CI) 64.1-68.1] in 2003 to 60.6% (95% CI 58.5-62.6) in 2006. Nevertheless, these rates are significantly higher than the 47% overall seroprevalence found in a 1988 study. Seroprevalence was higher in females than males and in older than in younger age groups in all four years examined. Ethnicity appeared to be related to seroprevalence with the highest rates found in Pacific Islanders (93.2%) and the lowest in Caucasians (54.8%). At least 38 242/39 960 (95.7%) seropositive donors were found to have seroconverted more than 12 months previously. Recent evidence suggests that such 'remote' seroconverters may pose a much lower risk of transfusion-transmitted CMV infection than recently infected seroconverting, but seronegative, blood donors.

Coexisting hereditary methaemoglobinaemia and heterozygous beta-thalassaemia.

Cyanosis was noted within a few weeks after birth in two sisters. On investigation the cause of cyanosis was found to be congenital methaemoglobinaemia due to NADH diaphorase deficiency. Heterozygous beta-thalassaemia was present as an additional incidental finding in one of the sisters, but did not contribute to the symptoms, thus showing that the two diseases, when coexistent, do not pose additional haematological problems. However, it is possible that the beta-thalassaemia counteracts the tendency to compensatory erythrocytosis induced by methaemoglobinaemia.

Disseminated intravascular coagulation in post-dysenteric haemolytic uraemic syndrome.

Coagulation studies were carried out in 14 children with haemolytic uraemic syndrome that followed acute dysentery. Stool cultures showed Shigella dysenteriae in 3 cases and were sterile in the remainder. Prolongation of the prothrombin time, activated partial thromboplastin time and thrombin time and raised levels of fibrinogen degradation products were found in 12 cases, indicating the presence of disseminated intravascular coagulation. Renal histologic examination showed cortical necrosis in 7 cases, which was extensive in 5 and patchy in 2. Disseminated intravascular coagulation may have a role in the pathogenesis of haemolytic uraemic syndrome associated with acute dysentery.