The current disclosure provides compositions, systems, and methods for detection and/or identification of antibodies. Also provided are compositions, systems, and methods that expedite and simplify processes to identify blood units that are clinically appropriate for transfusion into a recipient, and more generally to identify the presence of antibody(s) in blood that are specific for selected antigen(s). The systems and methods utilize genetically-modified (transgenic) non-target-organism red blood cells that express at least one antigen of the target organism species. This enables screening and identifying blood units faster, more consistently, at large scale, and/or with less dependence on human involvement.
