Reversible Agglutination of Trypsinised Red Cells by a M-Globulin Synthesized by the Human Foetus

Normal human cord sera contained a γM-globulin causing reversible agglutination of trypsinised compatible red cells. The agglutinating titre of cord serum never exceeded that of the corresponding maternal serum, but the ratio of the concentration in cord serum to that in maternal serum was higher for this agglutinin than for another γM-antibody and for total γM-globulin. It is concluded that the agglutinin was synthesized by the normal human foetus.