Abstract
Recent interest was revived in the human MN blood group system due to discovery of the MN precursor substance (T-antigen) on certain malignant, but not benign or normal tissues. Methods for preparing T-activated erythrocytes, anti-T lectin, anti-T absorbed human serum and purified anti-T antibody were described and should be useful to the researcher involved in this new line of investigation and to the routine blood bank faced with the occasional problem of erythrocyte polyagglutinability.