Characterization of adherence of nonotypeable Haemophilus influenzae to human epithelial cells

The adherence of 58 nontypeable Haemophilus influenzae isolates obtained fr om patients with otitis media or chronic obstructive pulmonary disease (COP D) and obtained from the throats of healthy individuals to Chang and NCI-H2 92 epithelial cells was compared. Otitis media isolates, but not COPD isola tes, adhered significantly more to both cell lines than did throat isolates . Since high-molec;lar-weight (HMW) proteins are major adhesins of nontypea ble H. influenzae, the isolates were screened for HMW protein expression by Western blotting with two polyclonal sera and PCR with hmw-specific primer s. Twenty-three of the 32 adhering isolates (72%) and only 1 of the 26 nona dherent strains were HMW protein or hmw gene positive. Among the 32 isolate s adhering to either cell line, 5 different adherence patterns were disting uished based on the inhibiting effect of dextran sulfate. Using H. influenz ae strain 12 expressing two well-defined HMW proteins (HMW1 and HMW2) and i ts isogenic mutants as a reference, we observed HMW1-like adherence to both cell lines for 16 of the 32 adherent isolates. Four others showed HMW2-lik e adherence to NCI-H292. Of the three other patterns of adherence, one prob ably also involved HMW protein. Screening of the isolates with six HMW-spec ific monoclonal antibodies in a whole-cell enzyme-linked immunosorbent assa y showed that the HMW proteins of COPD isolates and carrier isolates were m ore distinct from the HMW proteins from H. influenzae strain 12 than those from otitis media isolates. Characterization of the HMW protein of a COPD i solate by adherence and DNA sequence analysis showed that despite large seq uence diversity in the hmwA gene, probably resulting in the antigenic diffe rences, the HMW protein mediated the HMW2-like adherence of this strain.