ABO antibody titer performance characteristics and correlates between two automated platforms

BackgroundAABB standards require a policy for assessing transfusing ABO-incompatible plasma. After a fatal hemolytic event with incompatible plasma, our institution instituted platelet donor population titer method for ABO antibodies on the PK7300, with high-titer being defined as having isohemagglutinin titers greater than 256. We recently switched titering platforms to the Neo Iris and we seek to determine the equivalent isohemagglutinin high-titer cutoff on the Neo Iris as compared to the PK7300.MethodsWe measured the titers on 299 apheresis platelet donors and compared its performance characteristics at various cutoffs to the PK7300 reference standard. Discrepant results were manually diluted and retested on the Neo Galileo. Furthermore, since the Neo Iris is able to determine isotype and antigen specific titers, we also characterized these features in our donor population.ResultsIgM titer of 128 on the Neo Iris has better accuracy compared to the titer of 64 (94 % vs 93.6 %). Eleven of sixteen discordant results were in agreement with Neo Iris. Blood group O had the highest IgG antibody titers for both anti-A and anti-B (p = 8.4E-17 and 4.3E-09, respectively). Additionally, group O donors exhibited lower anti-A2 than anti-A1 IgG titers.DiscussionThe Neo Iris titer cut-off of 128 had the best overall accuracy and correlation with a 256 cut-off on our laboratory developed test on the PK7300 platform. Additionally, we found that group O donors had the highest titer antibodies, with typically higher IgG titers than IgM, and generally multiple dilution levels greater than other blood types.     

血小板悬浮血浆ABO血型抗体效价与保存时间消长性研究

目的研究单采血小板悬浮血浆中的抗-A和抗-B效价及其与保存时间的相关性。方法应用盐水凝集法检测血浆IgM抗-A、抗-B效价;应用2-巯基乙醇(2-Me)破坏IgM抗体后,抗人球蛋白法检测血浆IgG抗-A、抗-B效价。结果在保存期内A、B、O型单采血小板悬浮血浆中抗-A(IgM或/和IgG)或/和抗-B(IgM或/和IgG)效价间相互比较差异无统计学意义(P>0.05),其效价不随保存时间延长而降低(P>0.05);10%O型单采血小板悬浮血浆中抗-A和抗-B效价均较高。结论单采血小板输注时可不进行血液交叉配合试验,但须同型输注;尤其是O型悬浮血浆含较高的抗-A或/和抗-B(IgM或/和IgG)效价时,不能输注给其他血型患者。     

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.     

The characteristics of ABO antibodies in group O Thai blood donors

This study aimed to characterize anti-A and anti-B hemolysins, IgM, and IgG titers in Thai blood donors. Altogether, 300 serum samples from group O donors at the National Blood Centre, Thai Red Cross Society, were screened for anti-A and anti-B hemolysins and treated with 0.01 M dithiothreitol to characterize IgM and IgG titers by standard tube technique. Antibody titers were compared with hemolysis grade. Male and female ratio = 1:1.3 and ages ranged from 17 to 60 years. The overall prevalence of anti-A and anti-B hemolysins was 69%. Anti-A and anti-B hemolysins comprised 18.3% and 16.7%, respectively and 34% had both antibodies. High titers of anti-A hemolysins were associated with females (P< 0.05), and only anti-B IgM titers were associated with age (P< 0.05). Interestingly, the association of anti-A IgM titers, anti-A IgG titers, and hemolysin grade was demonstrated (P< 0.05). A significant association between hemolysin grade and anti-B IgM titers was found (P< 0.05). The prevalence of anti-A and anti-B hemolysins and high titers of IgM and IgG in Thais are high. Hemolysin grade showed significant associations with IgM titers; therefore, when providing ABO-incompatible platelet transfusion, especially for female plateletpheresis donors, IgM high titers of anti-A and anti-B screening is suggested.     

Antibodies to histo-blood group substances A and B: agglutination titers, Ig class, and IgG subclasses in healthy persons of different age categories

Isotypes and IgG subclasses of ABO antibodies from sera of 235 healthy blood donors were determined by an enzyme-linked immunosorbent assay (ELISA). Synthetic A and B trisaccharide-bovine serum albumin glycoconjugates were used for coating and monoclonal antibodies for the detection of heavy chain isotypes. Hemagglutination titers were determined in addition. Blood donors were between 20 and 67 years old, and at least 10 sera per 10-year age category and ABO blood group were included in this study. Antibody concentrations were expressed as a percentage of an internal standard, and sera with subclass-restricted anti-A and/or anti-B (anti-A/B) responses were used to normalize the ELISA values of IgG subclasses. A good correlation between the sum of the four subclasses and the total anti-A/B IgG values (rs = 0.81 for anti-A and 0.84 for anti-B) was obtained. IgG1 and IgG2 were the most predominant subclasses, but were found in various proportions in different individuals. Donor-to-donor variation exceeded age-related changes for all measured parameters. The correlation of anti-A IgM, IgG, IgA, and their sum with the agglutination titers was significant and revealed rs values of 0.70, 0.65, 0.65, and 0.80, respectively. For anti-B as well, the correlation of ELISA values with the agglutination titer was best when all three isotypes were added. We conclude that anti-A/B IgA, together with IgM and IgG, substantially contributes to the agglutination reaction. Potentially autoreactive antibodies were detected in sera of blood groups A, B, and AB.     

正常O型人血清ABO血型抗体主要类别的分析

目的通过检测O型及A/B型人血清中IgM类及IgG类抗体的效价,分析正常O型人血清中ABO血型抗体的主要类别。方法分别以盐水介质法和间接抗人球蛋白法检测O型及A/B型人血清中IgM类和IgG类抗A或抗B抗体的效价。结果 O型人血清中IgM类抗A/抗B抗体效价均显著高于IgG类抗A/抗B抗体（均P〈0.01）;O型人血清中IgM类抗A/抗B抗体效价与B/A型人比较无显著性差异（均P〉0.05）,而IgG类抗A/抗B抗体效价显著高于B/A型人（均P〈0.01）;O型人血清中IgG类与IgM类抗A/抗B抗体效价的比值均显著高于B/A型人（均P〈0.01）。结论 O型人ABO血型抗体仍以IgM类为主,但其IgG类抗体效价及在血清中所占的比例要明显高于A/B型人。     

微柱凝胶技术检测521例O型血孕妇IgG A(B)抗体效价

目的研究血型为O型的孕妇产前IgG A(B)抗体效价,以预防新生儿溶血病的发生。方法采用微柱凝胶法测定IgG抗-A(B)效价。结果 521例孕妇中,IgG抗-A(B)效价大于或等于1∶128者有288例,占49.66%。其中IgG抗-A效价大于或等于1∶128者有161例,占IgG抗-A总人数的54.03%,IgG抗-B效价大于或等于1∶128者有127例,占IgG抗-B总人数的45.04%。结论通过微柱凝胶免疫检测法检测孕妇血清血型抗体IgG效价能有助于诊断新生儿溶血病,指导临床干预措施。     

Significant numbers of apheresis-derived group O platelet units have "high-titer" anti-A/A,B: implications for transfusion policy

Transfusion of group O single-donor apheresis PLTs (SDP) to group A recipients has resulted in intravascular hemolysis and mortality. Owing to low availability of type-specific SDPs, transfusion services sometimes issue ABO-mismatched PLTs. After observing two cases of acute hemolysis following infusion of O SDPs to group A patients, where both recipient eluates revealed anti-A specificity, a prospective study to determine the prevalence of "high-titer" anti-A/A,B in group O SDPs was commenced. One hundred group O SDP samples were tested. Titers of at least 64 and/or 256 from either buffered (generally reflective of IgM antibodies) or anti-IgG gel cards, respectively, were considered critically high. Twenty-eight and 39 percent of samples revealed critically high anti-A/A,B IgM and IgG titers, respectively. IgM titers were at 1:64 (18%), 128 (6%), and 256 (4%), whereas IgG titers were at 1:256 (28%), 512 (7%), 1024 (2%), and 2048 (2%). The prevalence of critical anti-A/A,B titers in group O SDPs is relatively high. Thus, the risk of minor side ABO mismatch and potential intravascular hemolysis during group O SDP transfusion to group A recipients may be significant. Based on these data, a policy was instituted to test anti-A/A,B titers in O SDPs prior to "out-of-group" transfusion.     

Cryofiltration apheresis for major ABO-incompatible kidney transplantation.

The barrier of ABO-incompatible kidney transplantation is the presence of anti-A and anti-B antibodies in the recipient's circulating blood. Double filtration plasmapheresis (DFPP) is usually used to eliminate those antibodies. We tried cryofiltration apheresis (CRYO) in 2 recipients. Patient 1 was a 45-year-old male with B, Rh(+). The titers of IgM anti-A antibody were only reduced from x64 to x32 by the end of 3 sessions of standard CRYO. Renal allografting was not performed. Case 2 was a 29-year-old male with B, Rh(+). CRYO was introduced for 3 sessions. The initial IgM and IgG titers were x128 and negative, respectively. The standard CRYO system was modified by temperature, treated volume, and filter pore size. The IgM anti-A antibody titer was markedly reduced to x2 after the final session of CRYO. The donor was a 56-year-old father with A, Rh(+). Tacrolimus, azathioprine, methylprednisolone, and antilymphocyte globulin were used as the introductory immunosuppression therapy.     

新生儿ABO溶血病患儿母亲孕期IgG抗A/B效价的动态监测

目的动态监测O型孕妇不同孕期血清IgG抗A/B效价,为更加准确地预测新生儿ABO溶血病的发生提供诊断依据。方法通过对232例新生儿ABO溶血病的患儿母亲孕早期和孕晚期IgG抗A/B效价的动态监测,观察这类孕妇抗体效价的分布情况、变化率和变化幅度。结果这类孕妇的孕早期和孕晚期IgG抗A/B效价大多分布在≥1∶256,其中绝大多数孕妇（O-A：94.9%,O-B：95.8%）孕晚期的IgG抗A/B效价较孕早期有不同程度的升高;以升高2个滴度为主（O-A：46.3%,O-B：44.8%）。有11例其孕晚期的IgG抗A/B效价较孕早期无变化甚至发生降低,这11例孕妇孕早期的IgG抗A/B效价就偏高,主要分布在≥1∶512。结论动态监测O型孕妇不同孕期血清IgG抗A/B效价十分必要,可以将孕晚期抗体效价较孕早期升高2个滴度或以上作为提示ABO溶血的指标。     

应用ROC曲线评价产前IgG抗A(B)效价检测对早期诊断ABO新生儿溶血病的价值

目的 研究O型孕妇产前血清IgG抗A(B)效价对早期诊断ABO新生儿溶血病(HDN)的价值.方法 采用微柱凝胶法检测704例夫妻血型不同的O型孕妇产前血清IgG抗A(B)效价,用红细胞(RBC)直接抗人球蛋白试验、RBC抗体放散试验、血清游离抗体测定等3项试验确定患儿是否患有HDN,用受试者工作特性(ROC)曲线进行分...     

O型孕妇血型抗体效价与新生儿溶血发病率的关系分析

目的：研究。型RhD阳性孕妇（其丈夫为非O型）血清IgG抗-A（抗-B）抗体效价与新生儿溶血病（HDN）的关系。方法：应用微柱凝胶技术对382例O型RhD阳性孕妇进行了免疫性IgG抗A（B）抗体效价检测及对其新生儿进行HDN（①新生儿ABO、Rh系统定型;②新生儿直抗实验;③游离IgG测定;④放散实验）的检测。结果：382例O型RhD阳性孕妇中IgG抗-A（B）效价〈64者330例（占总数86．39％）,抗体效价≥64者13．61％。其中发生HDN5例,抗-A3例,抗-B12例,总发生率1．31％。结论：夫妇血型不合应及时检测孕妇IgG抗体,随着孕妇体内IgG抗体效价的增高,新生儿ABO溶血病的发病率也随之升高。孕妇产前应定时进行IgG抗体检测,了解效价与新生儿溶血病发病率之间的关系,对于预防新生儿溶血病极为有效。     

Age dependency of ABO histo-blood group antibodies: reexamination of an old dogma

Current textbooks for transfusion medicine state that anti-A and/or anti-B (anti-A/B) agglutination titers–and thus the respective antibody concentrations–reach their maximum in individuals 5 to 10 years old and then gradually decline with the increasing age of the individual. This statement is largely based on a study by Thomsen and Kettel that dates to 1929. In the present article, ABO antibodies in sera of 175 healthy persons aged 61 to 97 years, as well as sera of 170 newborn infants and children aged 0 to 17 years, were analyzed. Microhemagglutination tests were performed with all sera and complemented by ABO enzyme-linked immunosorbent assays to measure the immunoglobulin class (IgM, IgG, and IgA) of the anti-A/B. As in a previous study using sera of persons aged 20 to 67 years, individual differences exceeded age-related changes for all variables. Median values of IgG and IgA anti-A/B were elevated in elderly persons of blood group O, whereas no significant changes were observed in other variables. In particular, the decrease in agglutination titers with the increasing age of the individuals was far less pronounced than previously described; even in sera of persons aged 90 to 97 years, median agglutination titers of 128 were found. Results in the sera of children confirm previously reported data that agglutination titers and IgM anti-A/B reached adult levels at the age of 5 to 10 years.     

Preparation of single donor platelet with low antibody titers for all patients

Platelet concentrates from ABO-identical donors are the components of choice for patients. However, since inventories are generally insufficient and because there is usually a relative abundance of group O donors, perfect matches are not always possible. It is therefore the accepted practice for platelets to be transfused out of the ABO group when ABO-identical platelets are unavailable. Notwithstanding, the transfusion of platelets containing high titers of antibodies to the antigens on the red blood cells of the patient can cause clinically significant hemolysis. The way to improve the safety of group O platelets has focused on defining a safe level of antibodies or reducing the volume of incompatible plasma. In the current study, 107 group O single donor platelets (SDP) were modified after collecting the platelet pellet in a bag. The AB plasma was added instead of the donor's own plasma. The direct agglutination titers of anti-A/anti-B in the original group O SDPs' plasma were performed by doing a gel test, resulting in from 1:4 to 1:1024. The prevalence of high titers (i.e., at least 1:64 in our study) was relatively high, ～63% for anti-A and 78% for anti-B. The titer of residual anti-A/anti-B in the modified SDPs ranged from negative to 1:8. In most of the modified SDPs anti-A/anti-B could not be detected in the plasma (58.9% and 52.3%, respectively). The results indicate that our modified SDPs have very low titers; that is, acting as a universal SDP which is safe for all ABO patients. This modified SDP form is a more convenient way to overcome the risk from incompatible plasma or loss of platelets during the process of volume reduction and can help effectively manage our inventory.     

Unusual response to ABO incompatible blood transfusion

Three units of group A blood were inadvertently administered to a group O recipient during surgery without evidence of hemoglobinemia, hemoglobinuria, hypotension, disseminated intravascular coagulation, acute renal tubular necrosis, or other signs and symptoms of transfusion reaction. The recipient had normal concentrations of IgG, IgA, and IgM as well as complement (C3) prior to transfusion and anti-A agglutinins titered to 64 (titer of 128 by the antiglobulin technic). Seventeen hours following the transfusion, 28 per cent of the circulating red blood cells were group A (equivalent to 475 ml of packed cells); they were eliminated by day 5 without evidence of hemoglobinuria, hemoglobinemia or hyperbilirubinemia. Anti-A titers (antiglobulin) had risen from a posttransfusion low of 4 to 4,096 by day 10. After treatment of serum with 2-mercaptoethanol, however, hemolytic activity which was first noted on day 5 was lost and the antiglobulin titer dropped to 24 which suggested that most of the anti-A produced in response to the transfusion was IgM rather than IgG. The anti-A titer had dropped to essentialyy pretransfusion levels and the majority of anti-A present was IgM by day 91. The recipient suffered no untoward effects from the transfusion and was in good health three months following the transfusion.     

Identifying correlations between donor demographics and isohemagglutinin titers as a potential method to screen for low-titer group O whole blood

BackgroundWith more hospitals using low-titer group O whole blood in trauma resuscitation, having an efficient screening method for low-titer donors is critical. Our blood center uses an automated screen for high-titer isohemagglutinins in our platelet donations while collecting detailed donor demographic information. Using this data, we can identify key demographics often associated with titer status, thereby helping develop a donor-triaging method for titering.Study Design and MethodsTiter results were read with an automated microplate system as either high or low, based on agglutination, with a cutoff equivalent to 1:256 (both anti-A and anti-B). Donor demographic data analyzed included date of donation, blood group, age, gender, and ethnicity.Results57,508 donations were collected from 2073 unique donors between 2014 and 2018. We found the following demographics to be correlated with titer status: gender, ABO blood group, age, and ethnicity. Variability in titer status was identified in 215 individuals. This represented around 10 % of the total unique donors and was split equally amongst gender. We also found that donors between the ages of 41–60 ha d the highest likelihood of having variability in titer status, peaking at 13 %, and this proportion declined past age 60.ConclusionTiter status is associated with the following donor demographics: gender, ABO type, age, and ethnicity. We also discovered that variability in titer status is correlated with age. In blood centers that do not have automated and routine titer screening procedure, these findings could be used as a method to efficiently identify low-titer donors a-priori.     

血浆置换在ABO血型不相容的亲属活体肾移植中应用效果评价

目的 观察血浆置换在ABO血型不相容亲属活体肾移植中清除血型抗体的临床应用效果.方法 回顾分析2017年7月～2019年1月本院54例行ABO血型不相容肾移植患者的临床特征及行血浆置换治疗后血型抗体效价变化情况,分析血浆置换治疗过程中不良反应发生情况.结果 52/54例患者血型抗体(包括IgG和IgM)效价成功降至术前...     

3234名孕妇产前HDN特异性抗体筛查结果分析

目的探讨孕妇血型抗体效价与新生儿溶血病之间的关系。方法按照常规鉴定3 234对产前孕妇与丈夫ABO及RhD血型,采用微柱凝胶法技术检测夫妻ABO血型不合孕妇血清中的IgG抗-A、抗-B及抗-D效价。结果1901名夫妻ABO血型不合,产前抗-A或-B体效价>64的孕妇共1007名;其中O型980名,占97.32%;A型13名,占1.29%;B型14名,占1.39%;夫妻RhD不相合29对(0.90%),其中RhD(+)3例,抗-D效价≥256。结论新生儿溶血病主要发生在O型母亲怀有的A型或B型血胎儿,但并不能排除A或者B型血母亲所怀血型不合的胎儿。应对血型不合夫妇(特别是O型妇女)进行产前IgG抗-A或B效价检查,做到早预防、早治疗。     

ABO新生儿溶血病与O型孕妇血清中IgG及其亚类含量的相关分析

目的探讨O型孕妇血清IgG抗体及其亚型含量与新生儿溶血病(HDN)的关系。方法采用血型血清学方法,对317名夫妇血型不合的O型孕妇作IgG抗体效价检测,并对其中有妊娠史的287名孕妇作IgG抗体水平比较;采用ELISA法对71名HDN患儿及其母亲、65名健康O型孕妇和51名健康新生儿的IgG亚类作定量分析。结果1)317名新生儿中发生ABOHDN71例(22.4%),其中抗-A46例、抗-B25例;2)随着妊娠次数的增加,IgG抗体效价≥64者的比例和ABO-HDN发病率升高,>2次妊娠与第2次妊娠间有统计学差异;3)患儿及其母亲体内IgG抗体的含量显著高于正常对照组,且以IgG1抗体为主,患儿体内的IgG1比例(61.9%)高于母体(52.8%)。结论新生儿ABOHDN的发病率随其母亲体内IgG抗体效价的升高而升高,且与母亲体内IgG1呈正相关。夫妇血型不合的O型孕妇应定期检测IgG抗体及其亚类含量。     

孕妇产前IgG血型抗体效价测定及临床应用

目的观察孕妇产前体内IgG血型抗体水平及与新生儿溶血病的关系。方法采用微柱凝胶抗人球蛋白卡法对255例夫妇进行产前IgG血型抗体效价及ABO血型测定。结果在对195例夫妇ABO血型不合调查中,IgG血型抗体水平异常(≥64)阳性率为93.8%。其中IgG抗A(B)效价:64为12例(6.2%),64为12例(6.2%),128为60例(30.8%),256为39例(20%),512为45例(23.0%),1 024为27例(13.8%)。丈夫/孕妇血型组合为A/O与丈夫/孕妇血型组合为B/O两组间IgG抗体检出率比较,差异无统计学意义(χ2=4.361,P=0.499),AB血型的父亲其妻子抗体效价更高。结论对夫妇ABO血型不合孕妇产前IgG血型抗体效价测定有助于新生儿溶血病的产前预测,以利于尽早采取有效预防、治疗,减少新生儿溶血病的发病率,对于人口优生方面具有重要意义。