Positive Direct Antiglobulin Reaction in a Patient Population

Abstract

This study was undertaken to ascertain the incidence, the associated clinical diseases, and the serologic characteristics and significance of positive direct antiglobulin tests (DAT) in a hospital population. Forty-one (0.9%) of 4,664 medical-surgical patients had positive DAT's on admission. Eight of these 41 people also had antibodies in their sera. Twelve patients were taking alpha-methyldopa and one cephalothin, seven had malignant tumors, nine had immunologic disease, and 12 had miscellaneous conditions. Elution of antibodies from the erythrocytes of 36 patients was attempted: 17 eluates failed to react with panel cells; anti-K antibody was found in the eluates from two patients who had recently received transfusions; five eluates showed no blood-group specificity; and 12 agglutinated all panel cells. Eleven of the last 12 eluates, after absorption with Rh-negative cells, were tested with Rh cells of various phenotypes, and weaker or negative results with Rhnull cells were obtained with seven absorbed eluates. Three of the 41 patients had mild to overt hemolysis.

The role of the elution in antibody investigations

“…In some of the earlier studies, the rates of nonreactive eluates ranged from 47% to 91%. Our rate of nonreactive eluates was lower at 37.7% and this might relate to the elution reagent itself; in the earlier studies a variety of reagents were employed including dichloromethane, 4,8 ether, 2,5,9 xylene, 6 ethanol, 1 or various preparations using acidic pH to effect the elution including some commercially available kits 3,4,6‐8 . In our study we exclusively used a commercially available rapid acid elution kit, which might be more effective in recovering antibodies than the organic compound based methods, hence our lower rate of nonreactive eluates.…”

“…Elutions are also performed when ordered by a clinician in the course of diagnosing immune‐mediated hemolysis. In light of evidence that between 47% 1 and 91% 2 of DAT‐positive RBCs can feature a nonreactive eluate, and that eluates prepared from microscopically or weakly positive DATs are typically nonreactive, 3 we questioned how frequently eluates contributed novel serologic information under our reference laboratory's current policy or whether they should be performed in more selective serologic conditions.…”

Effect of Cell-Bound Proteins on the in vivo Survival of Circulating Blood Cells

“…Bohnen et al [73] found an incidence of 1 % positive DATs in a 13 years' study of hospitalized patients, where 17,110 DATs were performed. Lau et al [74] found an incidence of 0.9% positive DATs when testing 6,883 medical and surgical admis sions to the hospital. Lau et al [74] used only an anti-IgG reagent, and it is probable that when Bohnen et al [73] performed their study (1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962)(1963), the AGS was predomi nately anti-IgG.…”

“…Lau et al [74] found an incidence of 0.9% positive DATs when testing 6,883 medical and surgical admis sions to the hospital. Lau et al [74] used only an anti-IgG reagent, and it is probable that when Bohnen et al [73] performed their study (1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957)(1958)(1959)(1960)(1961)(1962)(1963), the AGS was predomi nately anti-IgG. More recently, a higher incidence of posi tive DATs in hospital patients has been re ported.…”

Strict vs Lenient Criteria for Elution Testing

“…1,7,8 A nonreactive eluate can be associated with medications, underlying disease states, and elevated globulin levels, all of which are unrelated to alloantibody formation. Eluates of this kind in no way affect transfusion practice.…”