Hepatitis B antibody in conventional gamma-globulin.

Recent lots of conventional gamma-globulin prepared from the plasma of outdated blood collected from voluntary donors in Massachusetts contain substantially more antibody (anti-HBs) to the hepatitis B surface antigen (HBs Ag) than do lots manufactured from plasma collected before 1970. Variations in titer of anti-HBs may have been related in part to local variations in the incidence of hepatitis B. However, data available since 1949 suggest that one must consider whether antibody excess (anti-HBs) or antigen excess (HBs Ag) prevailed among individuals contributing to the plasma pools. The titers of anti-HBs have continued to rise since 1971, when screening of blood donors for HBs Ag became mandatory, a step which presumably resulted in the removal of much of the HBs Ag that would otherwise adsorb anti-HBs. The anti-HBs titer in gamma-globulin routinely produced in Massachusetts now equals or exceeds the titer in other lots of gamma-globulin found to be effective in recent studies of preexposure prophylaxis of hepatitis B.