Decreased expression of mannose-specific adhesins by Escherichia coli in the colonic microflora of immunoglobulin A-deficient individuals.
Most Escherichia coli isolates can express type 1 fimbriae with mannose-specific adhesins. These adhesins bind to the oligosaccharide chains of secretory immunoglobulin A (IgA). Thus, in addition to specific antibody activity, secretory IgA possesses a broad reactivity with bacteria expressing type 1 fimbriae. The absence of secretory IgA in colonic secretions, as seen in IgA deficiency, might therefore alter the ability of type 1-fimbriated E. coli to colonize the large intestines of these individuals. In the present study, 10 E. coli isolates from each of 17 IgA-deficient and 17 age-matched control individuals were assessed for the carriage of the fim gene cluster by DNA-DNA hybridization and for the expression of type 1 fimbriae by hemagglutination of guinea pig erythrocytes. The contribution of type 1-fimbria-mediated adherence to HT-29 colonic cells was also analyzed. The proportion of fim+ E. coli isolates was lower in IgA-deficient than in control individuals (74 versus 94%, P < 0.05), as was the proportion of isolates expressing type 1 fimbriae in vitro (69% versus 85%, P < 0.05). The median mannose-sensitive adherence to HT-29 cells was lower for isolates from IgA-deficient individuals than from the controls (9 versus 26 bacteria per cell, P < 0.05). Isolates expressing type 1 fimbriae showed lower adherence to HT-29 cells when they were derived from IgA-deficient individuals than when they were derived from control individuals (15 versus 27 bacteria per cell, P < 0.05). The results suggest that the interaction of type 1 fimbriae with secretory IgA contributes to the large intestinal colonization by these bacteria.
Friman
V
V
Department of Clinical Immunology, Gotëborg University, Sweden.
Adlerberth
I
I
Connell
H
H
Svanborg
C
C
Hanson
L A
LA
Wold
A E
AE
D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D000368:Aged; D001665:Binding Sites; D016022:Case-Control Studies; D003106:Colon / Q000382:microbiology*; D004755:Enterobacteriaceae / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D017098:IgA Deficiency / Q000378:metabolism* / Q000382:microbiology*; D008297:Male; D008358:Mannose / Q000378:metabolism*; D008875:Middle Aged
D018829:Adhesins, Bacterial; D008358:Mannose