[Comparison of several methods for detecting anti-erythrocyte alloantibodies]

The efficacy of different methods for anti-red cell antibodies detection was assessed, variations being found in accordance with the specificity of the alloantibodies. The usefulness of enzyme tests in anti-Rh antibody detection was demonstrated, as well as that of low ionic strength saline solutions in detecting anti-Kell, anti-Duffy and anti-Kidd antibodies. Serum precipitation with 15% polyethyleneglycol 8000 previously to indirect antiglobulin test was found the most sensitive method, providing the best results in all the antibodies studied.

Atrial natriuretic peptide and cyclic guanosine-3',5'-monophosphate in normal and pathological pregnancies

The concentrations of atrial natriuretic peptide (ANP) and its presumed second messenger, cyclic guanosine-3',5'-monophosphate (cGMP) were determined in maternal plasma and amniotic fluid. Samples were obtained from normal and pathological pregnancies revealing hydramnios or severe Rh incompatibility between week 16 of gestation and delivery. For analysis of ANP and cGMP, radioimmunoassays were used. ANP and cGMP concentrations in maternal plasma did not differ in normal and pathological pregnancies. In amniotic fluid, we found ANP levels of about 120 pg/ml at 16 weeks of gestation which then decreased below the detection limit of 15.6 pg/ml. In contrast, cGMP levels were low at the beginning of pregnancy (4 pmol/ml) and rose significantly (14 pmol/ml), at the end of pregnancy. Pregnancies revealing severe Rh incompatibility exhibited the same levels as normal pregnancies when regular prenatal transfusions resulted in sufficient blood volume substitution. ANP, a volume-homeostasis-regulating hormone, is already produced in early pregnancy. The meaning of the presumed second messenger, cGMP, requires further investigation.

The 1987 Comprehensive Blood Bank Survey of the College of American Pathologists

The 1987 Comprehensive Blood Bank Survey consisted of four shipments of samples. Each presented graded challenges in ABO and D typing, crossmatching, and antibody detection and identification and ungraded challenges for antigen typing and ungraded serum samples for educational purposes. Practice patterns were elicited through supplemental questions, generally about issues raised by the survey samples. Two of the surveys showed significant problems. Set J-C included serum with anti-Lea, which was not detected by some participants. Anti-Dia was one of two antibodies in the J-D graded sample, and this additional antibody was not detected by a significant number of participants. Although minor problems were encountered in other challenges, in general performance was good.

[Transfusion of incompatible blood from the aspect of forensic serology]

Based on their own practice, the authors give an account of the possibility to use forensic serology when resolving problems of transfusion of incompatible blood in the ABO system. Conventional serological examination of erythrocytes and serum of the recipient--because of haemolysis of the administered blood cells--usually does not provide a picture of the antigenic structure of the donor and thus it does not provide evidence on transfusion of incompatible blood. According to practical experience examination of the blood stain of the recipient by the absorption elution test, incl. assessment of group antigens A and B, should be helpful, as the latter can be detected despite haemolysis of red cells. The authors recommend in subjects who died, to supplement the above procedure by the method of immunohistological examination of tissues to define more accurately their antigenic structure in the ABO system.

The importance of ABH antigens in platelet crossmatching

In the present study, the frequency with which ABH incompatibility could be detected in platelet crossmatches was determined. The effect of chloroquine elution on ABH antigens was also evaluated, and a technique was developed to remove IgG anti-A from group O plasma using a chemically synthesized human blood group A trisaccharide antigen covalently linked to crystalline silica (Synsorb-A). Group O plasmas were found to be incompatible with 52 percent of group A platelets and 17 percent of group B platelets (p less than 0.05). In contrast, anti-A from group B plasmas rarely produced a positive crossmatch, and no anti-B that reacted with platelets could be demonstrated in group A plasmas. IgG anti-A reactions with group A platelets were eliminated in 100 percent of the group O plasmas tested after treatment with the synthetic solid-phase immunoadsorption technique. Synsorb-A may be a useful adjunct to platelet serologic testing when group O sera need to be tested against A platelets. Group A platelets bound less anti-A after exposure to chloroquine, but only 17 percent of platelets became negative when crossmatched with group O plasma. It was concluded that increased IgG binding occurs in a majority of platelet crossmatches using a k-ELISA technique when group O recipients are tested against group A donors. These results offer a potential explanation for conflicting results in studies of transfusion results with ABH-incompatible platelets. Transfusions of group B platelets to incompatible recipients may be more likely to yield satisfactory increments than incompatible transfusions of group A platelets, but this remains to be proven. There appear to be significant differences between red cells and platelets in regard to serologic reactivity in the ABH system.

Significance of anti-A and anti-B isohemagglutinins in cord blood of ABO incompatible newborn infants: correlation with hyperbilirubinemia

Transcutaneous bilirubin index measurements (TcBI) were determined in ABO-incompatible term white newborn infants who had an indirect Coombs' test for detection of ABO incompatibility (ABO test) performed on cord blood. Serial transcutaneous measurements in the first 72 hours of life in 63 ABO test positive (group I) and 31 ABO test negative (group II) infants were compared with a control group of 109 term ABO compatible infants (group III). During the first phase of this study, the accuracy of TcBI was confirmed in 33 infants who had serum bilirubin determinations demonstrating a correlation coefficient of r = 0.93 between the jaundice meter index reading and total serum bilirubin. Determination of total serum bilirubin using TcBI did not show any statistically significant differences when groups I, II, and III were compared for maximum serum bilirubin values. These results reveal that a positive ABO test does not increase the predictive value of hyperbilirubinemia in ABO-incompatible white newborn infants.

The sensitivity and specificity of the immediate-spin crossmatch

The immediate-spin (IS) crossmatch is used to detect ABO incompatibility between donor red cells (RBCs) and the serum of the intended recipient. However, this test may be positive in the absence of ABO incompatibility (false positive) or it may be negative when ABO incompatibility exists (false negative). During a 25-month study, the rates of both false-positive and false-negative IS crossmatch results were evaluated, and the sensitivity and specificity of the IS crossmatch were determined. During the study period, 53,656 IS crossmatches were performed for patients without significant RBC antibodies. Fifty-five patients had positive IS crossmatches, and no false-negative reactions were found. In tests of 55 patients with positive IS crossmatches, 77 false-positive and 5 true-positive reactions were noted. The causes of the false-positive reactions were rouleaux (36 patients), cold-reactive antibodies (8 patients), a combination of rouleaux and cold-reactive antibodies (2 patients), fibrin clot (1 patient), and undetermined (3 patients). The sensitivity and specificity of the IS crossmatch were 100 and 99.86 percent, respectively. Laboratory personnel should be aware that the IS crossmatch may have false-positive or false-negative results, and they should develop written protocols to distinguish quickly between true-positive and false-positive reactions.

Effect of ABO mismatching on a radioimmunoassay for platelet compatibility. Successful adsorption of ABO alloantibodies with synthetic A and B substance

IgG and IgM anti-A and/or -B agglutinin titers were determined on 17 serum samples (5 group 0, 7 group A, 5 group B) to range from 8 to 1024. The presence of hemolysins was also evaluated. Single adsorptions with solid-state synthetic A and B substances greatly reduced or eliminated anti-A and -B titers but did not adsorb known platelet antibodies. Unadsorbed and adsorbed serum samples were crossmatched with ABO-compatible and -incompatible platelets by a radioimmunoassay employing 125I-labeled monoclonal antibodies specific for human gamma, mu, and C3d antigens. IgG and IgM crossmatch incompatibility was directly related to ABO alloantibody titers greater than or equal to 64. The use of adsorbed serum in the crossmatch eliminated or greatly reduced incompatible results that were due to ABO alloagglutinins alone, thus allowing the reliable detection of platelet and/or HLA antibodies.

Diagnostic fetal umbilical blood sampling in the management of isoimmunization

Current management of isoimmunization in pregnancy is predicted on the assumption that all sensitized women carry antigen-positive fetuses. In addition, management is based on indirect predictors of the magnitude of the fetal hemolytic disease. We present a preliminary report using a new approach of direct fetal blood sampling for the diagnosis and treatment of these patients. This form of evaluation provides specific information about fetal red blood cell antigen status and the degree of fetal anemia at an earlier gestational age than that validated by the Liley curves and eliminates empiricism from both the diagnosis and treatment of the isoimmunized pregnancy. The use of such a management protocol reduces the need for multiple invasive procedures in fetuses at little risk for disease and provides specific information about the status of those fetuses truly at risk.

Anti-Jka, -C, and -E in a single patient, initially demonstrable only by the manual hexadimethrine bromide (Polybrene) test, with incompatibilities confirmed by 51Cr-labeled red cell studies

Published reports have confirmed the superior sensitivity of the manual hexadimethrine bromide (Polybrene) test (MPT) for demonstrating many alloantibodies in vitro; however, the clinical significance of alloantibodies demonstrable exclusively by MPT has not been shown conclusively. A patient with macroglobulinemia experienced chills, fever, hemoglobinemia, and hemoglobinuria following the transfusion of 1 unit of red cells (RBCs) shown to be compatible by the low-ionic-strength antiglobulin (LIS-AG) method. Serologic investigation was negative. Intravascular hemolysis occurred with a second "compatible" unit. Serologic studies were again negative by LIS-AG and ficin-AG methods, but revealed anti-Jka by MPT. Both donors were Jk(a+b-), and 51Cr studies of the second donor's RBCs revealed a t1/2 of less than 30 minutes, with marked intravascular hemolysis. A LIS-AG-compatible Jk(a-) unit was transfused uneventfully, but with no rise in hematocrit. MPT next revealed anti-C; subsequent 51Cr studies with the Jk(a-), Cc donor's RBCs showed a 51Cr t1/2 of 100 minutes with slight intravascular lysis. Four transfusions of Jk(a-), C- blood were uneventful, but 5 days later the patient's hemoglobin declined. The following day, anti-E was demonstrable exclusively by MPT. 51Cr-labeled Jk(a-), C-, E- RBCs had normal 24-hour survival. The patient's hemoglobin rose to 11 g per dl following transfusions of Jk(a-), C-, E- RBCs, and he was discharged. In vitro studies employing the patient's purified IgM paraprotein revealed no interference with alloantibody binding or detection.

Interpretation of red cell survival data for in vivo compatibility testing: a normal value study

Short-term survival studies are sometimes required to determine the compatibility of donor red cells. The results of these studies are generally expressed as per cent survival at 60 min. The present study was undertaken to investigate the potential for more sophisticated data analytical techniques to improve sensitivity. In one group of eight healthy male volunteers, autologous red cells were labelled with 51chromium and injected immediately, while in a second group, red cells were stored for 5 d prior to injection. In both groups, eight to 10 samples were collected in the first 6 h and another 10-12 samples over the next 4 weeks. Estimation of the 60 min per cent survival was insufficiently sensitive to detect 'physiological' haemolysis following injection of 5-d-old autologous blood. Regression analysis of 6 h survival data, however, demonstrated significantly higher red cell clearance rates in these cases than in those receiving fresh cells, with a mean 24 h loss of 3.3% of activity. The upper limit for the 6 h red cell clearance rate was 1.63%/h after fresh autologous blood and 2.43%/h after 5-d-old blood. The significance of these findings is discussed and a protocol suggested for the analysis of short-term red cell survival data.

The UK National External Quality Assessment Scheme in Blood Group Serology. Compatibility testing 1983-1984: the influence of variables in test procedures on detection of incomplete antibodies

Error rates in exercises in compatibility testing varied between 3% and 36% over the six years 1979-1984. Evolution of serological procedures was continuous through this period but without clear evidence of improvement in performance of antibody detection although performance in the UK appears to be comparable with that elsewhere. Relationships have been established between a number of variables of reagents and techniques, and their performance. The influence of some variables is reasonably clear but there appear to be interactions between certain variables in their effects on performance, and interpretation is less straightforward. A test for agglutination of enzyme treated cells together with an antiglobulin test appears to be the most reliable combination for detection of incomplete antibodies in compatibility testing although one stage enzyme techniques are an inevitable compromise between reliability and convenience. Compatibility testing should not be considered in isolation from antibody screening in determining the optimum combination of tests for pretransfusion antibody detection.

Double failure of the Type and Screen

"Type and Screen" programs have proved effective in reducing time and cost in the crossmatching laboratories, while still assuring safety when transfusion is necessary. However, there remains the possibility that the program will miss a patient with an antibody to a low-incidence donor antigen and that such a patient will receive blood from such a donor. The authors report on the actuality of that possibility happening twice within two months in one hospital.