FIG. 2.

Analysis of host immune response to Tf and Lf receptor proteins from homologous and heterologous M. catarrhalis strains. Using hTf-Sepharose or hLf-Sepharose as the affinity matrix, we isolated receptor proteins from iron-starved cells of M. catarrhalis 4223, Q8, and N141. The proteins were eluted from the matrix by boiling in Laemmli sample buffer and subjected to SDS-PAGE (7% gel), and replicate Western blots were prepared. The blots were either stained for protein (A) or blocked and probed with convalescent-phase antisera (1/200 dilution) obtained from patients infected with M. catarrhalis N137 (B), N141 (C) or N132 (D).