Mg+ MNS blood group phenotype: further observations.

Red cells carrying the low-frequency MNS antigen Mg reacted with the only example of anti-DANE, an antibody which had previously defined the GP. Dane (Mi.IX) phenotype. Furthermore, Mg+ cells reacted with the original anti-Mur (serum of Mrs. Murrell), but with none of 14 other anti-Mur. Therefore, Mg+ cells carry both DANE antigen and an atypical Mur antigen. Immunoblotting of membranes from Mg+ cells with anti-M, and with eluates prepared from anti-Mg and Mrs. Murrell's serum demonstrated a glycophorin A (GPA) molecule whose mobility was increased by an apparent M(r) of about 3,000 presumably due to the loss of the three O-glycans known to be absent from Mg-active GPA.