Secretory IgA and bacterial adherence to nasal mucosal cells.

The ability of Streptococcus pyogenes to adhere to nasal mucosal cells was investigated by an in vitro assay system in order to clarify the actual role of secretory IgA in mucosal immunity in the nose. The number of bacteria adhering to isolated mucosal cells was significantly larger in patients with chronic sinusitis than in normal control subjects. The ability of bacteria to adhere, however, was significantly lower in the group of subjects having specific secretory IgA antibody activity to the M protein than in those having no secretory IgA activity. Findings demonstrated that mucosal immunity preventing or blocking the adherence of bacteria is impaired in patients with chronic sinusitis.