Comparison of solid-phase red cell adherence and microcolumn agglutination technology using untreated and enzyme-treated red blood cells.

Screening for clinically significant antibodies is crucial in transfusion medicine and is a routine part of pre-transfusion testing. The indirect antiglobulin test (IAT) is the most reliable and effective test for detecting clinically significant alloantibodies reacting at the antihuman globulin phase. Two of the main methods used for antibody detection and identification are solid-phase red cell adherence (SPRCA) and microcolumn agglutination technology (CAT), with or without enzyme-treated red blood cells (RBCs). This study was undertaken to detect and identify alloantibodies by performing antibody screen (ABS) and antibody identification (ABID) testing using SPRCA and CAT, with and without ficin-treated RBCs. Residual patient samples collected between 1 December 2020 and 19 May 2021 were saved, de-identified, and frozen at ≤-30°C before testing for alloantibodies. Seventy antibodies were detected in 53 samples among the 203 samples that underwent an ABS. Of those samples, 150 (73.0%) were nonreactive, 47 (23.1%) yielded positive results with both CAT and SPRCA, and six (3.0%) yielded positive ABS results with SPRCA only. Fifty-three samples that underwent ABID by both methods yielded eight samples with antibodies identified by SPRCA only. Additional enhancement of the CAT method by the use of ficin-treated RBCs was required to detect seven of the eight SPRCA-only antibodies; one sample remained nonreactive regardless. SPRCA testing detected clinically significant antibodies without the addition of enzyme-treated RBCs that was necessary in the CAT testing.

The Monocyte Monolayer Assay: Past, Present and Future.

Serologic testing using the indirect antiglobulin test (IAT) is known to be insufficient to determine the clinical significance or insignificance of a given antibody to red blood cells (RBC), particularly in cases of antibodies to high-prevalence antigens, such as anti-Ge or anti-Yta. An in vitro functional cellular assay, the monocyte monolayer assay (MMA), has been studied for more than 40 years for its potential use to differentiate between clinically significant and insignificant RBC antibodies. The MMA has recently been used to select donor blood for transfusion into patients having a serologically incompatible crossmatch, without any obvious sequalae. Thus, the MMA shows great potential for future use to select donor blood for transfusion in situations where antibodies to high-prevalence antigens or complex multiple alloantibody problems confront transfusion services. In this report, we review the history leading up to the current uses of the MMA, its optimization, and potential use for the selection of serologically incompatible donor blood for transfusion. We describe current ongoing work to document and improve the efficacy of the MMA. Finally, we briefly describe possible future directions to make the MMA more amenable to routine laboratories.