THE ANAMNESTIC ANTIBODY RESPONSE TO TYPE III SPECIFIC PNEUMOCOCCAL POLYSACCHARIDE

Rabbits immunized with killed type III pneumococci respond to anamnestic challenge by type specific polysaccharide (S III) with the synthesis of anti-S III antibody if a long interval is allowed to elapse between primary and secondary immunization. A study of the anti-S III antibody produced early and late in the immune response revealed no change in molecular class, banding pattern of dissociated light chains, or S III binding characteristics as measured under equilibrium conditions or by study of dissociation kinetics utilizing radioiodinated p-OH-benzyl-S III. Sequential booster injections of S III into rabbits primarily immunized with whole organisms 8 or 9 months earlier led to a progressive decrease in the number of animals showing successful anamnestic responses and in the magnitude of those responses. It is concluded that S III depletes the antigen sensitive cell population in the secondary response largely because of its limited ability to stimulate sustained proliferation by such cells.