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

Abstract

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.

Specificity of Natural Human Agglutinins against Red Cells Modified by Trypsin and Other Agents

“…Curd and maternal sera were chosen randomly from the sera previously tested (Mellbye 1966). The sera had been stored at -25" C.…”

“…The possible production of trypsin agglutinin by the normal human foetus (Mellbye 1966) suggests that the antigenic stimulus for this antibody is formed or revealed on own cells, since the foetus is generally held to be protected from antigens in the environments. This idea is supported by immunization experiments (Dodd et al 1953, Mellbye 1969 which indicated that the antigen is revealed on human red cells during their destruction in vivo.…”

“…Firstly, its agglutination is characteristically reversible, as the agglutinates disperse during prolonged incubation in undiluted or slightly diluted serum (Rosenthal & Schwartz 195 1 aib). Secondly, trypsin agglutinin is present in cord sera (Mellbye 1966), while at least Tagglutinin and periodate agglutinin are not (Lind McArthur 1947, Kipnis & Sacks 1955. The purpose of the present work was therefore to study the specificity of trypsin agglutinin, particularly with regard to its cross-reaction with human red cells treated with three other enzymes and periodate.…”

Properties of the Trypsinised Red Cell Receptor Reacting in Reversible Agglutination by Normal Sera

“…Buffered saline pH 7.4 was made as described previously (Mellbye 1966). THRC were prepared as described previously (Mellbye 1965), using bovine trypsin crystallized with MgSO, (Koch-Light Laboratories, Colnbrooks, Bucks., England).…”

“…The antigenic stimulus for the formation of this agglutinating antibody, which will be referred to as trypsin agglutinin, is unknown. However, the apparent production of trypsin agglutinin by the normal human foetus (Mellbye 1966) suggests that the antigen is produced in the foetus itself, as the foetus is generally considered to be protected from antigens in the environments. This idea is supported by immunization experiments (Dodd et al 1953, Mellbye 1969, which indicated that the antigen is revealed during the normal destruction of human red cells in vivo.…”