Final answer:
The basic technique used to detect unexpected antibodies in a sample using a commercial set of reagent cells is the Enzyme-linked immunosorbent assay (ELISA), which is sensitive and allows for quantification of antibodies.
Step-by-step explanation:
The basic technique used to detect unexpected antibodies with a commercial set of reagent cells is Enzyme-linked immunosorbent assay (ELISA). ELISA involves coating a plastic plate with the antigen associated with potential antibodies. A patient or test serum is then applied; if the serum contains the antibodies in question, they will bind to the antigen on the plate. After washing away non-specific bindings, a secondary antibody linked to an enzyme is added, which, in turn, binds to the first antibody if present. Upon adding a chromogenic substrate, a color change will occur, indicating the presence of the antibodies. This technique is sensitive and allows for the quantification of specific antibodies in the plasma or serum.