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Keeping the pH constant during the incubation of sample and complement solutions was an inportant factor to obtain a reproducibla ACA value. Lyophilized complement shows a pH of 8.8-9.0 after reconstitution. The pH of frozen complement is 7.2-7.4. When the ACA of an intravenous IgG (IVIG) was tested with the reconstituted complement, the ACA value was higher than when the preparation was tested with frozen complement.Ionic strength also affected the ACA test of an IVIG which did not contain ionic substances such as NaCl or glycine. Even when the pH and ionic strength of commercial IVIG preparations were standardized by dialysis, the concentration of IgG polymer did not necessarily correlate with the ACA value.

A method for the heat treatment of human IgG solution at 60 degrees C for 10 h was established. Human immunodeficiency, mumps, vaccinia and 4 other viruses were added to the IgG solution in 33% sorbitol and heated at 60 degrees C. Those viruses were inactivated within 1 h. Heat-treated intravenous IgG (IVIG-H) was prepared by heat treatment and polyethylene glycol (PEG) fractionation. Conventional nonheated intravenous IgG (IVIG-C) was prepared from the same source paste by the fractionation method. No physicochemical or biological difference was observed between the heated and control IVIG preparations.

Before HBsAg screening of plasma was instituted, the preventive effect of immunoglobulin preparations (ISG) against Hepatitis B was not clearly defined. Since HBsAg screening became a requirement, all ISG has shown Anti-HBs and it further became clear that such preparations are effective in preventing Hepatitis B.Recently, cases of Hepatitis NANB associated with administration of intravenous immunoglobulin (IVIG) were reported. Since there is no NANB screening test presently available and IVIG tends to be administered in a large volume, a virus inactivation treatment should be performed on IVIG.Now that heat treatment at 60°C for 10 hours, which had previously been considered to be impossible or unnecessary for immunoglobulin, has become possible, an intravenous immunoglobulin preparation which is more ideal in stability and safety is available.