Response to Oligosaccharide-Protein Conjugate Vaccine againstHemophilus influenzaeb in Two Patients with IgG₂Deficiency Unresponsive to Capsular Polysaccharide Vaccine

In healthy persons IgG antibodies to polysaccharides are predominantly of the IgG2 subclass.1 2 3 Selective deficiency of this subclass is associated with inability to produce antibodies to bacterial capsular polysaccharides, which confer protective immunity to encapsulated bacteria. However, the basis of the relation between antibody responses to capsular polysaccharide and the IgG2 subclass has not been defined. Some insight into that mechanism is offered by the present study of two children with selective IgG2 deficiency and a documented lack of antibody response to immunization with the capsular polysaccharide vaccine of Hemophilus influenzae b. Both patients were subsequently immunized . . .