Antibody affinity and immune complexes after immunization with tetanus toxoid in protein-energy malnutrition

Protein-energy malnutrition reduced the affinity of antibody to tetanus toxoid, particularly after primary immunization. The effect on antibody affinity was more marked in patients with hypoproteinemia than in those with marasmus. Hemagglutinating antibody levels were comparable in undernourished and well-nourished groups. Circulating immune complexes were detected in eight of 21 children with protein-energy malnutrition and in one of the controls. Differences in antibody affinity in malnutrition may be an important determinant of altered host resistance and of complications of disease in nutritional deficiency.