Mucosal barrier mechanisms. Interplay between secretory IgA (SIgA), IgG and mucins on the surface properties and association of salmonellae with intestine and granulocytes.

Rough Salmonella typhimurium 395 MR 10 bacteria sensitized with SIgA were used to assess the effect of secretory IgA (SIgA) on bacterial association with the intestine of rat and with a column of hog gastric mucin, and on IgG-mediated surface properties and interaction with polymorphonuclear leucocytes. It was found that SIgA increased the affinity for mucus belt of the intestine and for the mucin column, but reduced IgG-enhanced phagocytosis and surface hydrophobicity and charge of the bacteria. It is suggested that the ability of SIgA to render bacteria mucophilic and to modify IgG-mediated reactions serve the purpose of secluding bacteria from contact with mucosal membranes and depress inflammatory reactions at the site of infection.