Abstract
Affinity (KR) of antibody to human serum transferrin in New Zealand mice was measured by a globulin precipitation technique. KR was low in mice immunized early in life, increased with age of immunization up to 16-26 weeks, and then fell to low levels. KR in young and old NZB mice was increased by immunization with antigen in Freund's complete adjuvant. The correlation between low affinity antibody production and susceptibility to immune complex disease is discussed.