Antitoxic and antiviral antibodies in Cohn fractions of human plasma.

Titrations of diphtheria, tetanus, poliomyelitis and measles antibodies have been made on large pools of plasma from Canadian blood donors and on immune serum globulins (ISG) and other plasma protein fractions prepared by cold alcohol fractionation. The mean level of tetanus antitoxin in ISG made from plasma collected between 1954 and 1965 was 10·8 units/ml and is showing a tendency to increase. The mean level of diphtheria antitoxin in these preparations of ISG was 5·3 units/ml and has not shown any tendency to increase. In ISG made from plasma collected during 1963–65 the levels of poliomyelitis neutralizing antibodies have been constant and have averaged five times the potency of the N.I.H. Reference Poliomyelitis Immune Globulin. Measles antibodies in the 1963–65 ISG preparations have also shown a constant level, averaging 0·42 times the potency of the N.I.H. Reference Measles Serum. The yield of both antitoxins and virus antibodies in ISG (Fraction II) was close to 60% of that present in the starting plasma. Fraction III contained an average of 13% of the antibody activity of starting plasma. Mercaptoethanol treatment of plasma failed to inactivate significantly any of the antitoxin or antivirus activities studied, indicating that little if any of these antibodies was attributable to immunoglobulin of the IgM class.