Secretory immunoglobulin A and G antibodies prevent adhesion of Escherichia coli to human urinary tract epithelial cells.

The adhesion of Escherichia coli to human urinary tract epithelial cells was inhibited by commercial gamma globulin, the total immunoglobulin fraction of human breast milk and urine, as well as the isolated immunoglobulin G and secretory immunoglobulin A fractions of urine from patients with acute pyelonephritis. Urinary anti-O6 antibodies reduced the adhesion of several O6 strains. Absorption of antibodies to the lipopolysaccharide of the adhering strain markedly decreased the antiadhesive capacity of all the immunoglobulin preparations, whereas elimination of antibodies to the capsular polysaccharide antigen consistently had a small but not significant effect. When urine was absorbed with whole, live bacteria of the patients' infecting strains, the antiadhesive effect completely disappeared. Absorption with bacteria lacking pili only partially reduced this effect.