Malcolm L. Beck

A solid‐phase antiglobulin test

A solid‐phase antiglobulin test was developed as an alternative to hemagglutination for compatibility testing. The solid‐phase endpoint of red cell adherence allowed results to be read visually or spectrophotometrically. This method was easier to perform than a hemagglutination antiglobulin test and had increased sensitivity without loss of specificity.

Solid‐phase ABO grouping and Rh typing

A solid‐phase adherence method (SPAM) for ABO grouping and Rh typing of red cells (RBCs) has been developed. Adherence reactions were read spectrophotometrically and interpreted by a computer. The SPAM had a 99.6 percent correlation with conventional microplate agglutination methods for ABO grouping and Rh typing. The increased sensitivity of the SPAM was demonstrated because it directly detected Du‐positive RBCs and weak subgroups of A and B.

Red blood cell polyagglutination: Clinical aspects

Polyagglutination is the term applied to red blood cells (RBCs) that are agglutinated by almost all samples of human sera from adults but not by autologous serum or sera of newborns. The polyagglutinable state may be transient or persistent. Transient polyagglutinability results from the exposure of normally cryptic antigens by bacterial enzymatic activity during the course of an infectious process. RBCs are polyagglutinable because most sera from adults contain agglutinins for the exposed antigens. This type of polyagglutination can often be reproduced in vitro with bacterial culture fluids or isolated enzymes. Persistent polyagglutination may be a consequence of somatic mutation leading to a cellular lineage characterized by an enzyme deficiency that results in exposure of a normally cryptic antigen, Tn. Most human sera contain anti-Tn. Tn polyagglutination is regularly accompanied by leukopenia and thrombocytopenia and has been associated with leukemia. Other forms of persistent polyagglutination are due to the inheritance of rare blood groups or are associated with a hematologic dyscrasia.

Hemolytic disease of the newborn associated with anti-Jk3.

This report documents a mild case of hemolytic disease of the newborn (HDN) associated with anti‐Jk3. The Filipino mother had previously had six children none of whom had been affected by HDN. She had been transfused at the time of her second pregnancy. Anti‐Jkb and anti‐Jk3 were detected in the maternal serum at the time of her seventh delivery. No prenatal serologic tests for blood group antibodies had been performed. The cord blood was found to have a positive direct antiglobulin test and anti‐Jkb plus anti‐Jk3 were eluted. The infant was treated with phototherapy.

Red cell compatibility testing: A perspective for the future

T HIS REVIEW traces the evolution of red cell compatibility testing from its origins in the early years of the 1900s to the testing protocols in use as the century closes. The various procedures conceived reflected the state of knowledge at the time particularly concerning red cell alloantibody detection. Each new antibody detection method developed was incorporated into the current version of the serological compatibility test. When testing protocols became so comprehensive, timeconsuming, and expensive, some workers recognized that thousands of abbreviated emergency cross-matches had proved no less safe. The purpose of the cross-match was then legitimately questioned. The answers revealed that for more than 95% of patients, compatibility testing was used to confirm ABO compatibility. Various cost-effective strategies were then developed to secure ABOcompatible transfusions in unsensitized patients. Modern abbreviated compatibility testing systems, designed as final pretransfusion tests of ABO compatibility, differ little from the first crossmatches conceived in the early 1900s. At the beginning of the 20th century, transfusion of blood from one human to another was technically feasible, albeit cumbersome. Two significant barriers, soon to be overcome, remained. The ABO blood groups were described by Landsteiner in 1901,1,2 and the use of sodium citrate as an autocoagulant was introduced in 1915. 3 Thus, by the early 1900s a rational immunohematologic basis for the frequent hemolytic reactions that had hitherto bedeviled blood transfusion was available. Nevertheless, fatal hemolytic transfusion reactions continued to be reported more than 5 years after Landsteiners publications, indicating that, for a variety of reasons, the value of pretransfusion testing was not generally recognized and was actually regarded by some as needless meddling. 4,5

A Serum Haemagglutinating Property Dependent upon Polycarboxyl Groups

Summary. A serum agglutinin reactive with red cells in the presence of polycarboxyl groups is reported. It is likely that this represents an additional example of the type of agglutinin previously described as agglutinating red cells in the absence of ionized calcium.

Solid-Phase Techniques in Blood Transfusion Serology

For nearly a century, erythrocyte agglutination has persisted as the most widely used method for the demonstration of antigen-antibody reaction in immunohematology. So far, no other system has been developed which can match its simplicity, versatility, and general reliability. The major disadvantage of agglutination reactions is the lack of an objective endpoint, which has severely hindered attempts to automate routine pretransfusion tests. To overcome this problem, we have designed a series of solid-phase assays for ABO and Rh grouping, antibody screening, compatibility, and hepatitis tests. Each of these solid-phase assays shares a common endpoint of red cell adherence, which is easily interpreted visually or spectrophotometrically. Computer interface permits the automatic interpretation and recording of results. We believe this solid-phase system should finally bring the blood bank laboratory into the age of automation.

Coexistent Tk and VA Polyagglutinability

Serologic investigations of the red blood cells of two patients indicated polyagglutination as the cause of compatibility problems. Lectin studies to classify the variety of polyagglutination demonstrated the simultaneous exposure of two latent membrane receptors, Tk and VA. It is proposed that different bacterial enzymes were responsible.

The Immunoglobulin Structure of Human Anti‐M Agglutinins

Fifty examples of human anti‐M agglutinins were subjected to reductive cleavage using both 2‐mercapto‐ethanol (2‐ME) and dithiothreitol (DTT). Thirty‐nine (78%) were resistant to inactivation by sulphydryl compounds indicating IgG composition. This was confirmed by column chromatography. The remaining eleven sera were sensitive to reduction cleavage. There was no obvious association of immunoglobulin composition of the antibody with previous immune exposure to the M antigen. These results confirm observations in the literature that anti‐M agglutinins are an exception to the generally expected correlation of saline agglutinating activity with IgM structure.

Unexpected Limitations in the Use of Commercial Antiglobulin Reagents

The majority of antiglobulin sera used in blood banks in the USA are commercially prepared immune rabbit sera, designed to be reactive only with human red blood cells sensitized with immunoglobulins or complement components. Current manufacturing methods result in a product that gives reliable specific reactions provided that the test red blood cells are normal, particularly with respect to sialic acid levels. This report describes our findings of false positive antiglobulin tests caused by incompletely absorbed antiglobulin reagents when cells with low sialic acid levels were tested. An evaluation of nine commercially prepared antiglobulin reagents revealed, in many of them, the presence of anti‐species antibody, anti‐T, and anti‐Tn. Blood bank personnel must be aware of these characteristics especially when testing either enzyme premodified or polyagglutinable cells. The use of incompletely absorbed reagents might account for positive direct antiglobulin tests that are encountered occasionally in apparently normal healthy individuals. Furthermore, recent protocols advocating the use of trypsinized cells for the evaluation of anti‐C3d activity of antiglobulin sera are invalid if the reagent is inadequately absorbed of anti‐species agglutinins.