QUALITATIVE AND QUANTITATIVE-ANALYSES OF THE ANTIBODY-RESPONSE ELICITED BY HAEMOPHILUS-INFLUENZAE TYPE-B CAPSULAR POLYSACCHARIDE TETANUS TOXOID CONJUGATES IN ADULTS WITH IGG SUBCLASS DEFICIENCIES AND FREQUENT INFECTIONS

Twenty-one IgG subclass-deficient adult patients with repeated infecti ons of the respiratory tract, were immunized with Haemophilus influenz ae type b capsular polysaccharide (HibCP) covalently bound to tetanus toxoid (TT). Specific immunoglobulin and IgG subclasses to HibCP and T T were quantified; the biological activities of HibCP antibodies were also investigated. Most patients showed an antibody response similar t o that observed in healthy adults, and the bactericidal activity relat ed to the post-immunization levels of HibCP antibodies. No relation wa s found between immunoglobulin isotype deficiency, the clinical sympto ms and the IgG subclass responsiveness, and no relation was observed b etween HibCP and TT antibody responses. Our data indicate that some, b ut not all, patients with recurrent infections and IgG subclass defici ency have an abnormal serum antibody response to polysaccharide and pr otein epitopes of Hib-TT conjugate vaccine. Analysis of the antibody r esponse after vaccination with HibCP-TT conjugate vaccine did not seem to predict the clinical course of such patients.