Patricia A. Arndt

Predicting the clinical significance of red cell alloantibodies using a monocyte monolayer assay.

Few data have been published that correlate in vitro monocyte monolayer assays (MMA) and red cell (RBC) survival in patients with alloantibodies of unknown significance. Over the past 6 years we gathered clinical correlations in 12 patients with the following antibodies: anti‐Lan (three patients), ‐Ge (three patients), ‐Yta (five patients), and ‐Ytb (one patient). RBC survival was estimated using 51Cr studies in seven patients and follow‐up of transfusion of incompatible blood in the other five. Six patients with no evidence of RBC destruction had negative MMA findings (anti‐Lan [one patient], ‐Ge [two patients], and ‐Yta [three patients]). Five patients with evidence of in vivo RBC destruction had significant MMA results. The two clinically significant anti‐Lans required fresh serum to give a meaningful MMA result. One patient (anti‐Ytb) had an MMA result of borderline significance‐normal 51Cr RBC survival at 1 hour‐but a reduced T50Cr. The MMA we used appeared to predict the clinical outcome of transfusion in every patient with antibodies to high‐frequency antigens whom we tested.

A retrospective analysis of the value of monocyte monolayer assay results for predicting the clinical significance of blood group alloantibodies

BACKGROUND:  Cellular assays (e.g., monocyte monolayer assays [MMAs]) have been used to predict the clinical significance of red blood cell (RBC) alloantibodies.

Selection of platelets for refractory patients by HLA matching and prospective crossmatching.

A multi‐site clinical study compared platelets chosen for refractory patients by prospective platelet crossmatching using stored donor platelets and HLA‐based selection. Seventy‐three patients who were refractory to random‐donor platelets received two plateletpheresis components, one chosen by HLA‐based criteria and the other by crossmatching. Patients were carefully evaluated to exclude nonimmune factors that could adversely affect transfusion results. Each of the five study sites used a crossmatch procedure with which it had experience. Results from this study indicate the following: 1) The overall rate of successful transfusion was similar when an HLA‐based method of donor selection that includes all grades of matching and mismatching was compared to a crossmatch‐based method of donor selection. 2) HLA‐based selection that restricts recipients to grade A and BU matches was superior to a selection method based upon crossmatching alone. Donor selection based on HLA matching (grades A or BU) was also superior to selection based on any degree of HLA mismatching (grades BX, C, or D). 3) Selection of donors based on HLA‐ cross‐reactive groups (defined by in vitro serologic crossreactivity) was no more successful than that based on grade C and D mismatches and was no more successful than selection by crossmatching alone. 4) Lymphocytotoxic and platelet antibodies were not detected in many of the enrolled patients, even though patients demonstrating nonimmune factors were eliminated from the study. It can be concluded that HLA‐ compatible (grades A and BU) platelets provide optimal support for refractory patients, but that crossmatch‐selected platelets are acceptable as an alternative component.

Serology of antibodies to second‐ and third‐generation cephalosporins associated with immune hemolytic anemia and/or positive direct antiglobulin tests

BACKGROUND: First‐generation cephalosporins rarely caused immune hemolytic anemia (IHA). Second‐ and third‐generation cephalosporins, especially cefotetan and ceftriaxone, are increasingly associated with severe, sometimes fatal IHA.

Positive direct and indirect antiglobulin tests associated with oxaliplatin can be due to drug antibody and/or drug-induced nonimmunologic protein adsorption.

BACKGROUND: Two patients were suspected of having immune hemolytic anemia (IHA) due to oxaliplatin. A related drug, cisplatin, is known to cause nonimmunologic protein adsorption (NIPA). Studies were performed to determine the presence of oxaliplatin‐dependent antibodies in addition to oxaliplatin‐induced NIPA.

Serological studies of piperacillin antibodies.

BACKGROUND: Penicillin‐induced immune hemolytic anemia (IHA) is associated with immunoglobulin G antipenicillin detected by testing penicillin‐coated red blood cells (RBCs). Antibodies to piperacillin, a semisynthetic penicillin, would be expected to react similarly; however, antipiperacillin can be detected by testing in the presence of the drug. Piperacillin is commonly used in combination with tazobactam, which causes nonimmunologic protein adsorption onto RBCs. In six cases of piperacillin‐induced IHA, reactivity with piperacillin‐coated RBCs was not similar to reactivity of antipenicillin with penicillin‐coated RBCs.

Clinical significance of anti-Jra: report of two cases and review of the literature.

BACKGROUND: Jra is a high‐frequency antigen seen in all populations, but the clinical significance of Jra antibodies is incompletely understood. Two cases are reported in which patients with anti‐Jra received incompatible transfusions.

Cross-reactivity of cefotetan and ceftriaxone antibodies, associated with hemolytic anemia, with other: cephalosporins and penicillin.

Most drug-induced immune hemolytic anemias since the late 1980s have been caused by the second- and third-generation cephalosporins, cefotetan and ceftriaxone, respectively. Cross-reactivity of cefotetan and ceftriaxone antibodies with other cephalosporins or penicillin has been studied only minimally. We tested 7 serum samples previously identified to contain cefotetan antibodies and one serum sample previously identified to contain ceftriaxone antibodies against 9 other cephalosporins, penicillin, and 7-aminocephalosporanic acid in the presence of RBCs and also used hapten inhibition to indicate cross-reactivity. Serum samples containing cefotetan antibodies showed some cross-reactivity with cephalothin and cefoxitin (and to a much lesser extent with penicillin and ceftazidime). The ceftriaxone antibodies showed very weak cross-reactivity with cefotaxime, cefamandole, and cefoperazone. There was very little cross-reactivity between cefotetan antibodies and the drugs tested in the present study. We have no data to determine whether the in vitro data relate to in vivo reactivity.

Blood doping in athletes - detection of allogeneic blood transfusions by flow cytofluorometry.

Athletes may undergo blood transfusion to increase their red cell mass and the oxygen carrying capacity of their blood in order to confer a competitive advantage. Allogeneic transfusions are normally mismatched at one or more minor blood group antigens. The most sensitive and accurate method known to detect this form of blood doping is flow cytometry. Low percentages of antigen‐positive and antigen‐negative red blood cells (RBCs) can be quantitated using suitable specific alloantibodies and careful analysis. By testing blood samples taken at various times, a reduction in the percentage of a minor population of RBCs will indicate transfusion has occurred. Am. J. Hematol., 2008.

Rhnull red blood cells with reduced CD47 do not show increased interactions with peripheral blood monocytes

We wish to take the opportunity to respond to Piel et al, who have pointed out their differing experience of hepatic venoocclusive disease (VOD) in patients taking thiopurines during maintenance therapy for childhood acute lymphoblastic leukaemia (Stoneham et al, 2003). They also found a higher incidence of VOD, but at a lower frequency than we reported. The overall incidence in their group was 5Æ5% compared with 12% in ours. The male sex bias that we saw was not evident in their cohort. More concerning perhaps, is the frequency of long-term sequelae that the authors describe. This contrasts markedly with our group who appeared mostly to suffer a mild, reversible toxicity. Possible explanations for a differing incidence and outcome might be related to the patient cohorts considered. We had limited our patient review to all patients that had received a minimum of 1 year of maintenance therapy. In addition, we had excluded all patients who had developed VOD or significant liver dysfunction related to the intensification blocks. Our decision to limit this patient group was based on the consideration that there may be additional confounding variables at play during intensification that could contribute to the hepatotoxicity of thiopurine-related VOD. We have had two patients who have developed VOD related to intensification blocks containing thioguanine. Both patients have persistent features of hepatotoxicity that have not resolved, including abnormal liver function tests, splenomegaly and thrombocytopenia. Thus, in Dr Piel’s cohort, six of nine patients would not have been eligible for our review. Our two index cases were diagnosed retrospectively after cessation of therapy. Both patients took longer to resolve their splenomegaly and thrombocytopenia than the remainder of the cohort; perhaps indicative of greater toxicity and subsequent liver damage. Following the recognition that thrombocytopenia may be a sentinel sign of VOD, all patients at our centre with persistent thrombocytopenia on maintenance therapy were actively investigated for VOD. In other words, we used different inclusion criteria and encountered a higher incidence of milder reversible disease, probably because we developed a low threshold for recognizing the problem and thus were looking for it. We would not be surprised that VOD associated with multiagent intensification blocks or prolonged exposure to thioguanine in the face of thrombocytopenia (or both) may be more severe and likely to produce persistent or progressive liver damage. The gender difference we saw may, of course, be due to chance. However, as the Marsden patients are not really comparable, we feel that there may still be an important question to answer here concerning male:female differences in thiopurine metabolism.