A comparison of results from antihuman globulin-graded reactions with the monocyte monolayer assay

Blood transfusions are a common medical treatment. Risks arise when compatible blood is not available. This study assesses the correlation between antibody reaction strength at the antihuman globulin (AHG) phase of testing and the antibody clinical significance as predicted using the monocyte monolayer assay (MMA). Multiple examples of anti-K donor plasma samples were selected to sensitize K+k+ red blood cells (RBCs). Reactivity was confirmed by testing the sensitized K+k+ RBCs at saline-AHG. Antibody titers were determined by serial dilution using neat plasma. Sixteen samples were selected for the study based on comparable graded reactions with neat plasma (1+, 2+, 3+, and 4+) and similar titration endpoints. Each sample was used to sensitize the same Kk donor and then tested by monocytes to evaluate the clinical significance using the MMA, an in vitro procedure that mimics in vivo extravascular hemolysis to predict the survivability of incompatible transfused RBCs. The monocyte index (MI), i.e., the percentage of RBCs adhered, ingested, or both versus free monocytes, was calculated for each sample. Regardless of the reaction strength, all examples of anti-K were predicted to be clinically significant. While anti-K is known to be clinically significant, the immunogenicity rate of K ensures ample supply of antibody samples for inclusion in this project. This study demonstrates that in vitro antibody strength is highly subjective and variable. These results show no correlation between graded reaction strength at AHG and the predicted clinical significance of an antibody as assessed using the MMA.

Heat Curing and Delayed Ettringite Formation

This paper reports some preliminary results from a study of the effect of elevated temperature curing on mortars and the phenomenon of delayed ettringite formation (DEF). Mortars made from cements with sulphate levels of 3%, 4%, and 5% and with 5% sulphate and added alkali were cured at 20 and 90° C and subsequently stored in water. Expansion measurements showed a pessimum effect with increasing S03 content. Mortars which expanded showed a corresponding decrease in strength. X-ray diffraction (XRD) studies indicated that no ettringite is present after heat treatment but re-forms over time within the material. However, the ultimate levels of ettringite reached do not correspond to the magnitude of expansion observed. X-ray microanalysis shows that immediately after the heat treatment the aluminate species and most of the sulphate species are incorporated within the C-S-H gel. The concentrations of these species decrease during expansion, such that at the end of expansion the amounts remaining correspond to the presence of AFm phase mixed with C-S-H.