Characterization of antibodies produced by S-s- individuals

Historically, classification of U- and U variant (U+var) individuals has been made by hemagglutination and adsorption and elution studies performed with polyclonal U antisera. Molecular studies and serologic tests with a potent monoclonal anti-He have shown that U+var red cells, some of which are He+, possess an altered form of glycophorin B.

Seventeen sera, previously determined to contain anti-U, were tested with a panel of red cells of common and rare MNS types.

Five sera contained anti-U only, and 12 sera contained broadly reactive antibodies with apparent, but inseparable, anti-U,He or anti-U,N,He specificities.

The majority of antibodies produced by S-s-U- individuals are anti-U plus anti-glycophorin B and are analogous to the broadly reactive antibodies produced by En(a-) individuals whose red cells lack glycophorin A or have altered glycophorin A. To avoid further immunization of patients with anti-U, sera used for classification of S-s-U- donors should be selected to detect S-s- red cells that possess altered forms of glycophorin B.