Quantitative Measurement of “Natural” and Immunization-induced Haemophilus influenzas type b Capsular Polysaccharide Antibodies (original) (raw)

Extract: Haemophilus influenzae type b antibodies were measured quantitatively in normal and immunized humans and in commercially available pooled immunoglobulin. A “protective” serum level was estimated to be 0.06 to 0.1 $mUg antibody/ml based upon the anti-type b concentration in normal adult sera and pooled immunoglobulin. An age-related difference characterized the adult and infant serum antibody response to injection of the purified type b capsular polysaccharide. The adults responded with higher and sustained antibody levels than the infants and children. An immunized infant reacted with type b antibody formation after nasopharyngeal carriage of H. influenzae type b and two infants reacted with type b antibodies after enteric carriage of Escherichia coli with a cross-reacting antigen.

Speculation: Qualitative and quantitative differences characterize the adult versus the infant re-response to the capsular polysaccharide of H. influenzae type b. This age-related difference in the serum anti-type b antibody response may be due to the development of differentiated cells induced by whole bacteria, either as H. influenzae type b or by other organisms with cross-reacting antigens. The “protective” level of serum anti-type b antibodies, estimated by two methods, was achieved by immunization of infants, which suggests that this procedure may confer protective immunity.