ANTIBODIES OF HAEMOPHILUS-INFLUENZAE TYPE-B POLYSACCHARIDE AFFECT BACTERIAL ADHERENCE AND MULTIPLICATION

Since immunization of infants with conjugated Haemophilus influenzae t ype b (Hib) capsular polysaccharide (PS) vaccines results in a reducti on of colonization, we determined the inhibitory effect of anti-sib PS on two steps in the colonization, i.e., adherence of H. influenzae to nasopharyngeal epithelium and bacterial growth. Monoclonal antibody ( MAb) E117-5 specific for Hib PS inhibited at a concentration of at lea st 80 mu g/ml in vitro the adherence of Hib strain 770235f(+)b(+) to o ropharyngeal epithelial cells by 50% (P < 0.02), but this MAb and sera from children immunized with Hib PS conjugate vaccine (n = 10) were n ot inhibitory in final dilutions containing up to 20 mu g of anti-Hib PS per ml. The growth of Hib strain 770235f(+)b(+) did completely stop in the presence of 5 mu g of anti-Hib PS MAb E117-5 per ml and human sera with an anti-Hib PS concentration of 2 mu g/ml or more, in contra st to the growth of the nonencapsular variant strain 770235f(+)b(0).