E. A. Steiner

Electronic verification of donor-recipient compatibility : the computer crossmatch

Background: This article describes standard operating procedures (SOPs) for a computer crossmatch to replace the immediate‐spin crossmatch for ABO incompatibility between patient blood samples submitted for pretransfusion testing and the blood component selected for transfusion. These SOPs were developed following recent changes to the Standards for Blood Banks and Transfusion Services of the American Association of Blood Banks (AABB).

The evaluation of a positive direct antiglobulin test (autocontrol) in pretransfusion testing revisited.

Direct antiglobulin tests (DATs) using anti‐IgG were performed on 65,049 blood samples from prospective transfusion recipients; 3570 tests (5.49%) were positive. Using criteria published previously (primarily excluding patients not transfused within the preceding 14 days), 778 samples from other than neonatal patients were selected for further evaluation. Eluates that did not react were obtained on 518 (66.6%) of these samples. Warm‐reactive autoantibodies were apparent in 192 eluates, while 16 contained drug‐related antibodies, anti‐A or anti‐B from prior transfusion with ABO mismatched blood components, or anti‐D passively acquired from immune serum globulin. Fifty‐two eluates contained alloantibodies; however, in only six of these cases did the corresponding serum lack unexpected alloantibodies, as determined by routine pretransfusion studies. Three additional weakly reactive clinically significant alloantibodies were detected solely through additional serum tests performed on DAT‐positive samples.

Discrepancies in reverse ABO typing due to prozone. How safe is the immediate-spin crossmatch?

Three group O sera manifesting prozone in reverse ABO tests are reported. All were implicated in erroneous blood typing results. One sample failed to react with A1 red cells (RBCs) in immediate‐spin (IS) tests, had anti‐A and ‐B titers of 8192 and 2048, respectively, by indirect antiglobulin technique (IAT), and was from a diabetic patient; the parenteral administration of A substance present in porcine insulin is a possible cause of hyperimmunity in this case. The second sample was from the recipient of a single unit of group B fresh‐frozen plasma; the serum anti‐A and ‐B titers were 10,240 by IAT, but only weak reactions with A1 and B RBCs were noted in routine IS reverse typing tests; the hyperimmunity in the patient concerned was likely due to crossreacting anti‐A, B stimulated by B‐active glycoproteins and/or glycolipids in the transfused plasma. The third serum also had anti‐A and anti‐B IAT titers of 10,240 but did not react with A1 and B RBCs by IS; the hyperimmunity in this case may be related to sepsis from intestinal flora carrying A‐ and/or B‐like antigens. These antibodies lysed A1 and/or B RBCs in tests incubated at room temperature (RT) and strongly agglutinated those RBCs by IS when diluted 10‐fold with saline. The absence of the prozone phenomenon in tests with RBCs suspended in diluents containing EDTA is consistent with the previously published mechanism for anti‐A prozone: namely, the steric hindrance of agglutination by the C1 component of human complement. In addition, weak (≤ 1+) anti‐A/‐B agglutination without lysis was also seen with 5 of 231 other sera in 2‐minute RT tests, but all five reached ≥3+ by IS and lysed A1 and/or B RBCs in 5‐minute RT tests. These findings raise concerns regarding the ability of the IS crossmatch to detect ABO errors, particularly if tests are not centrifuged immediately. While prozones in true IS tests are rare, failure to detect anti‐A/‐B due to C1 blocking occurs more frequently in tests left briefly at RT. Accordingly, use of EDTA is indicated when IS crossmatches are performed to demonstrate ABO incompatibility.

The evaluation of a positive direct antiglobulin test in pretransfusion testing.

The results of serologic studies on 879 blood samples with a positive direct antiglobulin test (DAT) are presented. All blood samples were from patients who were either anemic, for reasons other than blood loss, recently transfused, or had serum antibodies detected during routine pretransfusion tests. Blood samples from only 81 of the patients included in this study had serologically reactive eluates (64 autoantibodies, three antibodies to penicillin and cephalothin treated red blood cells, three passively acquired anti‐A antibodies, and 11 transfusion‐induced alloantibodies). The eluted antibodies were also detected in the serum by routine pretransfusion tests in 13 of the patients whose red blood cells eluted autoantibodies, and in five of the patients whose red blood cells eluted transfusion‐induced alloantibodies. All but one of the 11 transfusion‐induced alloantibodies were detected within 14 days posttransfusion. Based on these findings, a cost‐effective and safe approach to the management of blood samples with a positive DAT would be to restrict the preparation and testing of eluates to those samples from recently transfused patients. It is the contention of the authors that the incorporation of the DAT in pretransfusion testing should primarily serve to detect alloantibody formation before such antibodies are evident in the serum, and should not be used to screen patients for unsuspected autoimmune hemolytic anemia. Furthermore, the authors question the necessity for blood banks to routinely perform an autocontrol on all blood samples from prospective transfusion recipients.

Role of the crossmatch in testing for serologic incompatibility

Nine unexpected antibodies of unquestioned clinical significance were detected when the major crossmatch was performed on 31,320 pretransfusion blood samples from 8969 patients whose screening test for unexpected antibodies was nonreactive. Three of the antibodies retrospectively were found to manifest a positive screening test. Another antibody was not detected by the antibody screening test due to an error in preparation of the screening red blood cells. The overriding importance of the major crossmatch is the assurance of ABO compatibility between donor blood and recipient. Therefore, while this study does not resolve whether the antiglobulin phase of the procedure might be considered optional, the major crossmatch should not be eliminated.

Clinical and Laboratory Findings on Two Patients with Naturally Occurring Anti‐Kell Agglutinins

Two patients with naturally occurring anti‐K agglutinins are reported. Both patients manifested clinical symptoms associated with septicemia. Transfusion of one patient with K‐positive blood did not result in hemolytic complications, further stimulation of the anti‐K agglutinin or any change in its immunoglobulin nature.

Serological Studies on an Α-D-Galactosyl-Binding Lectin Isolated from Bandeiraea simplicifolia Seeds

Abstract. The serological characteristics of a highly purified α‐D‐galactosyl‐binding lectin, isolated from extracts of Bandeiraea simplicifolia seeds, are described. These studies show that the lectin preferentially agglutinates group B red cells and in addition has the capacity to distinguish between group A1 and group A2 erythrocytes.

Anti-lea as an autoantibody in the serum of le(a - b+) individual.

The first example of anti‐Lea, as an autoantibody, in the serum of a phenotypically Le (a–b+) individual is described. The patient is a 55 year old male with squamous cell carcinoma of the esophagus. His saliva contains Lea, Leb and H substances, and inhibits the hemagglutinating activity of his serum anti‐Lea. The Leb antigen content of his red blood cells is approximately half that of control Le (a–b+) red blood cells. The patients disease process may be responsible for the development of this unexpected autoantibody.

Can the reading for serologic reactivity following 37 degrees C incubation be omitted

The need to detect antibodies that agglutinate and/or hemolyze red cells (RBCs) directly at 37 degrees C, but do not react in subsequently performed indirect antiglobulin tests (IATs), is of concern relative to the streamlining and automation of antibody detection methods. To determine incidence and significance of such reactions, data from 87,480 tests, which used low‐ionic‐strength saline, 10‐minute incubation at 37 degrees C, and anti‐IgG, were analyzed for unexpected antibodies. There were 3590 positive tests, of which 475 showed reactions at 37 degrees C but not in subsequently performed IATs (37 + IAT‐). Of these, 196 reactions were due to autoantibodies or other factors usually considered insignificant with respect to the survival of transfused incompatible RBCs, 176 were due to alloantibodies of questionable clinical significance (M, Lea, P1, etc.), and 103 were associated with alloantibodies of potential clinical significance (63 E, 27 K, 5 Jka, 4 D, 3 cE, and 1 C). This latter reaction was seen in 72 patients, with two 37 + IAT‐antibodies occurring in each of 3 patients. Of the 75 potentially significant 37 + IAT‐antibodies, 57 were seen in patients recently exposed to homologous RBCs, 13 in patients with a history of transfusion and/or pregnancy, and 5 in patients with no known exposure to homologous RBCs. IAT reactivity was observed in subsequent samples with 27 of these antibodies. The predictive value of a 37 + IAT‐test was 21.7 percent for a potentially significant antibody. The incidence was 0.12 percent of all tests for unexpected antibodies. As 27 potentially significant 37 + IAT ‐ antibodies were found in subsequent samples to be IAT +, indicating a secondary (IgG) immune response, elimination of the 37°C reading for agglutination and hemolysis should not be undertaken lightly.

Percutaneous umbilical blood sampling and umbilical vein transfusions: rapid serologic differentiation of fetal blood from maternal blood

Percutaneous umbilical blood samples (PUBS), obtained under ultrasound guidance, are used for prenatal diagnosis and management of hemolytic disease of the newborn (HDN) and other fetal disorders. Rapid testing at the time of sampling is vital to distinguish fetal from maternal blood. Blood typing was performed by slide technique in the treatment room during 38 procedures on 25 patients. Anti‐l was used to test 50 presumed PUBS; venous l‐positive maternal blood was tested in parallel. Because anti‐l cannot detect fetal blood after umbilical vein transfusion (UVT) of l‐positive donor blood, ABO and Rh blood typing reagents were used to test 29 samples when maternal and fetal or donor blood groups differed. Monoclonal reagents were used for optimal detection of weak AB antigens in fetal blood. Avid, chemically modified anti‐D was used for Rh typing. Blood typing showed 27 (34%) of 79 samples to be maternal blood. Fetal blood was obtained in 8 of 10 cases investigated for fetal disorder and in 16 cases of potential HDN (anti‐D, 5; ‐CD, 5; ‐cE, 2; ‐K, 2; ‐c; ‐E). The absence of HDN (antigen‐negative fetus) was determined in 4 cases. UVT afforded live birth of 9 of 10 infants with HDN and was not indicated in two cases