Standardization of IgG subclass antiserums for use with sensitized red cells

The only IgG subclass antiserums standardized for use with red cells are those sold by the Netherlands Red Cross. Their recommended method is a sedimentation antiglobulin test (AGT) not generally used in the USA. Some years ago we tested the antiserums for sensitivity and specificity using the routine centrifugation AGT and found the methods comparable. More recently, we have become concerned since the antiserums are being used by a variety of methods other than the recommended procedure. It is well-known that it is difficult to prepare subclass antiserums without contaminating antibodies to other IgG markers. Thus, we thought it worthwhile to standardize the antiserums with particular emphasis on specificity using several different technics. We found that some methods that have been used to define the subclass of red cell-bound IgG were inappropriate, and led to many false positive results.

A LISS spin enzyme method for the detection of red cell antibodies and its use in routine antibody screen procedures

A technique for performing the enzyme phase of the antibody screen on red cells suspended in low-ionic-strength-salt solution (LISS) is described. The reliability of this LISS spin-enzyme (LSE) technique was compared with the two-stage papain-tile method, in the detection of 62 previously identified enzyme reacting antibodies. All 62 antibodies examined were detected by the LSE method, and no false-positive reactions were found. Using LSE and papain-tile methods in parallel, further assessment was obtained by screening 2000 sequential blood samples under routine service conditions. Fifty-six blood samples contained alloantibodies, of which 43 reacted by both methods, eight by the LSE method only, and five by the papain-tile method only. It was concluded that the LSE method was comparable to the papain-tile method.

A detailed serological study of five anti-Jka sera reacting by the antiglobulin technique

Detailed serological investigation of five examples of anti-Jka revealed considerable heterogeneity in their characteristics. All the sera were investigated by the antiglobulin technique, with and without complement and by a range of sensitization and testing methods. Three were readily detected in the presence of complement, while two were detectable with anti-IgG, providing a spin test was used. Complement was bound by all and resulted in enhanced reactions, particularly when slide/tile tests were used. The study emphasizes that anti-complement (C3) is an essential component of polyspecific antiglobulin reagents used in cross-matching, enabling the ready detection of these clinically important antibodies.

Cytotoxicity of anti-PP1Pk antibodies and possible relationship with early abortions of p mothers

IgG and IgM anti-PP1Pk antibodies of human sera from p individuals were examined for their ability to agglutinate red blood cells (RBC) of various P phenotypes and to mediate ADCC of these RBC by human effector cells. Agglutinating antibodies were found in either the IgG or the IgM fraction, while ADCC active antibodies were found mainly in the IgG fraction and were essentially cytotoxic with Pk RBC. The possible relationship of these antibodies with early abortions of p mothers is discussed.

Detection and significance of granulocyte alloimmunization in leukocyte transfusion therapy on neutropenic dogs

Studies were carried out in dogs to detect alloimmunization to granulocytes by indirect immunofluorescence (GIIF) and to determine the significance of cross-matching in selecting donors for immunized recipients. All recipients were rendered neutropenic (less than 500 per microliter) by chemotherapy. Three groups of transfusions were evaluated. Group I consisted of 14 transfusions administered to sensitized dogs that were GIIF-negative with donor cells; Group II, 12 transfusions to the same dogs with GIIF-positive donor cells; Group III, 16 transfusions to nonimmunized control dogs. At 1 hour following transfusion, circulating granulocytes demonstrated increments of 956 +/- 137 per microliter (mean +/- SEM) in Group I dogs compared to 236 +/- 57 per microliter for Group II (p less than 0.001). Group III transfusions yielded increments of 888 +/- 116 per microliter, not significantly different from Group I. GIIF correlated better with transfusion results than granulocyte cytotoxicity or lymphocyte cytotoxicity tests or leukoagglutination cross-matching. Nineteen sera with alloantibodies to granulocytes were produced by random or intrafamilial immunizations with granulocytes. Partial characterization of specificities showed that granulocyte specificities were independent of DLA, and consistent with a genetic system of dominant alleles. It was concluded that a) alloimmunization to granulocytes is detected by the GIIF, b) positive tests predict transfusion effects, and c) a genetic system independent of DLA could be recognized on dog granulocytes.

Fetal Rh blood group determination in pregnancy termination by dilatation and evacuation

Feasibility of Rh blood group determination from fetal samples at the time of second trimester abortion by dilatation and evacuation method was investigated. Fetal cord blood was found to be obtained easily, especially when gestational age was more than fifteen weeks. Fetal blood typing was performed easily and accurately. Selective prophylactic immunization of Rh negative patients undergoing dilatation and evacuation procedures is suggested.

A clinically significant erythrocyte antibody detectable only by 51Cr survival studies

Hemolytic transfusion reactions typically are explained by red cell serologic incompatibilities. We describe a patient in whom a clinically significant red cell alloantibody could not be demonstrated, despite the occurrence of several clinically severe hemolytic reactions. Serologic studies using multiple techniques demonstrated only an anti-Bga; these studies included standard procedures as well as more sensitive experimental techniques. A 51Cr survival study using red cells from a random unit, compatible in vitro with conventional techniques, showed 72 percent survival at 1 hour and 7 percent survival at 24 hours. R2R2 (hr" (e) negative) red cells in a second 51Cr survival study showed 90 percent survival at 1 hour and 92 percent survival at 6 hours. The patient was transfused with R2R2 units which were tolerated well and survived normally. Extensive serologic testing still demonstrated only an anti-Bga. A third 51Cr survival study, 10 months after the first study, with an R1R1 (hr" (e) positive) sample showed 90 percent survival at 1 hour and 42 percent survival at 6 hours. A fourth study using a larger aliquot of R2R2 (hr"(e)negative) 51Cr-labeled red cells, examined over 2 weeks showed a near normal 21-day survival of 50 percent. These 51Cr survival studies, along with normal survival of hr" (e) negative units, suggest that this patient destroys hr" (e) positive red cells despite negative serologic testing.

Placental transfer of Rh antibody (anti-D IgG) during pregnancy

Anti-D levels in blood taken immediately postpartum from Rh-negative women who have been given antenatal Rh immune globulin and the anti-D levels in the cord blood of their babies were measured semiquantitatively by a low ionic polybrene Auto Analyzer technique. When both mother and baby were Rh-negative a comparison of their anti-D levels was made against the interval between injection of the passive anti-D and delivery. Mothers' levels decreased as the interval increased, the regression coefficient for 73 maternal sera was -0.74. The drop in levels of cord blood was much less than that of the mothers' levels. The regression coefficient was -0.294 for 74 cord sera (one set of twins). The marked difference between cord blood and maternal blood levels of anti-D at delivery supports the hypothesis that the transfer of IgG across the placenta is predominantly from mother to fetus and not from fetus to mother.

Detection of fetal hemorrhage in Rh immune globulin candidates. A rosetting technique using enzyme-treated Rh2Rh2 indicator erythrocytes

Current serologic tests occasionally fail to identify women needing more than one vial of Rh immune globulin. We compared the indirect antiglobulin test after incubation with anti-D and a rosetting technique using enzyme treated Rh2Rh2 erythrocytes as methods for identifying significant fetal maternal hemorrhage (FMH). Artificial mixtures containing 0.05 to 1.2 percent Rh1rh (CcDe) fetal red blood cells mixed with rh (ce) adult red blood cells were tested. The indirect antiglobulin test of the 0.6 percent mixture (approximately 30 ml FMH) was reported to be microscopically positive by 17/20 technologists; whereas, 20/20 found the rosetting test to be strongly positive. The volume of FMH in 118 postpartum Rh immune globulin candidates was quantified using Kleihauer's test and formula. The results of the rosetting and Kleihauer tests of blood specimens from these patients were negative 1.4 ml for two, and strongly positive rosetting test and FMH of 6.5 ml for one. The rosetting test utilizes routine blood banking skills and requires 5 minutes more "hands on" time than an indirect antiglobulin test. Confirmation and quantification of positive results by an acid-elution test is necessary.

Detection and quantitation of fetal maternal hemorrhage utilizing an enzyme-linked antiglobulin test

Existing methods to evaluate fetal-maternal hemorrhage depend upon red blood cell agglutination or blood film elution techniques. These tests are insensitive and difficult to quantitate and reproduce. An enzyme-linked antiglobulin test was evaluated to determine its suitability for clinical testing of postpartum candidates for Rh immune globulin administration. Prepared mixtures of Rh positive fetal and Rh negative adult red blood cells approximating fetal maternal hemorrhage ratios of 0-2.0 percent were studied. In 43 assays, the enzyme-linked antiglobulin test consistently detected Rh positive fetal red blood cells in the 0.5 and 0.25 percent mixtures representing a 25 ml and a 12.5 ml hemorrhage, respectively, in a 70-kg woman. The 0.125 percent red blood cell suspension was positive in 85 percent of the assays and the 0.0625 percent suspension was positive in 56 percent of the tests. Agglutination testing by Du variant technique failed to detect 25 percent of the 0.5 percent mixtures. Only 45 percent of tests with the Rh immune globulin crossmatch detected the 0.5 percent mixture. A modified Kleihauer-Betke procedure was as sensitive, but less reproducible than the enzyme-linked antiglobulin test. Forty-seven Rh immune globulin candidates were studied to assess the quantity of fetal maternal hemorrhage. Fourteen patients (29.8%) had detectable Rh positive red blood cells by enzyme-linked antiglobulin tests but all hemorrhages were less than 12 ml; agglutination tests did not detect any fetal red blood cells. We conclude that the enzyme-linked antiglobulin test is a simple, sensitive, and objective procedure for detecting small amounts of Rh positive red blood cells in Rh negative blood and should be applicable to clinical testing of post-partum Rh immune globulin candidates.

Erythrocyte autoantibodies, autoimmune haemolysis and pregnancy

The clinical and serological records of 20 pregnant patients with erythrocyte autoantibodies were critically reviewed and analysed. This series, the largest reported, confirmed an association between erythrocyte autosensitization and pregnancy, and suggested that this occurred on an average of 1 in 50,000 pregnancies. The clinical presentation varied from severe haemolytic anaemia to serological abnormalities discovered during the routine testing of well patients; overt haemolysis was present in 7 cases. Treatment was only necessary in 3 patients where the haemolysis was severe. 3 infants were mildly affected with haemolytic disease due to the maternal autoantibodies crossing the placenta but no treatment was needed. The risks to the infant were increased when other active autoimmune conditions (e.g., systemic lupus erythematosus) were present. With early diagnosis and appropriate treatment, outlook for mother and child is good.

Biochemical assessment of fetal lung maturity

The relationship between the enzyme phosphatidate phosphohydrolase (PAPase) and lecithin/sphingomyelin (L/S) ratio in amniotic fluid was evaluated in normal human pregnancies and in several pregnancies complicated by Rh isoimmunization. An increase in PAPase activity in amniotic fluid appears to parallel the increase in L/S ratio after 33 weeks gestation in normal subjects. These data suggest that amniotic fluid PAPase may originate from the fetal lung and play a role in the regulation of the synthesis os lecithin. Its usefulness as an indicator of fetal lung development requires further correlation and confirmation.

Quantitation of ABO mixed-cell populations by a peroxidase-anti-peroxidase immunoenzyme method

The peroxidase-anti-peroxidase immunoenzyme method was applied to red blood cell ghosts for the detection of ABO mixed-red blood cell populations. Red blood cell ghosts produced by acid-glycine lysis eliminated previous problems due to distorted red blood cell and hemoglobin-associated peroxidase activity. Anti-A,B was used to discriminate between various mixtures of test cells in group O cells. The positive-stained minor population of test cells stained dark brown following application of the peroxidase-anti-peroxidase method and the nonreactive group O cells were counterstained light blue with Coomassie brilliant blue which facilitated quantitation. The expected and observed numbers of positive-stained cells per 1000 cells were not significantly different as computed by X2. As low as a 0.5 percent minor population in an ABO red blood cell mixture could be accurately quantitated by this method.

Laboratory identification of erythroblastosis fetalis

The clinical laboratory assumes the paramount role of supplying accurate data to the attending physician for the diagnosis, treatment and prevention of HDN. Maternal prenatal testing identifies patients at risk for Rh-HDN. The antibody titer is of primary value in assessing patients as candidates for amniocentesis. Amniotic fluid analyses provide an assessment of fetal prognosis in HDN and also an assessment of gestational age, lung maturity, and placental function. In severe HDN, amniotic fluid analysis can indicate the need for intrauterine transfusion. Postnatal laboratory studies can confirm the suspected diagnosis of HDN, identify those neonates at risk of developing kernicturus, and provide the physician with information pertaining to the treatment of HDN. Finally, prenatal and postnatal laboratory testing identifies those females eligible for Rh-immune globulin therapy to prevent HDN in subsequent pregnancies.