High intraluminal fluid flow increases intestinal IgA output.
BACKGROUND
Stool IgA output in normal stool or chronic diarrhoea is a fraction of that recorded in high-output watery diarrhoea due to cholera. We hypothesized that high intestinal fluid flow leads to increased IgA output, and this is not a consequence of reduced degradation/reabsorption.


METHODS
Daily intestinal outputs of IgA and other secretory and non-secretory proteins were measured in stool from 14 volunteers with ileostomies and compared with the output during whole-gut lavage, a whole-gut perfusion system.


RESULTS
Output into whole-gut lavage was significantly higher for all the proteins (P=0.02 to 0.001). Median IgA output into ileostomy effluent (IE) was 3.6 mg/kg/day compared with 26 mg/kg/day into whole-gut lavage fluid (WGLF). Thus IgA recovery in stool was only 12.7% of the amount in corresponding WGLF. Similar results were found for other proteins: specific IgA and IgM antibodies (5.4%-20.3%), IgM (42.4%), IgG (8.9%), and albumin (9.3%). Six subjects with IE water content >92% had increased recovery of IgA compared with eight with <92% water. In vitro, experiments predict that degradation of IgA within the small bowel results in 80% remaining compared with the 12.7% measured in vivo.


CONCLUSIONS
Our data show that high intraluminal fluid flow increases the intestinal output of IgA and other proteins, and this is not a consequence of reduced degradation/reabsorption in the colon or small bowel. This increased protein output may be a non-specific response in the early stages of acute diarrhoea.
Croft
N M
NM
Gastrointestinal Laboratory, Faculty of Medicine, University of Edinburgh. Western General Hospital, UK.
Ferguson
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D007081:Ileostomy; D007070:Immunoglobulin A / Q000032:analysis / Q000096:biosynthesis*; D007075:Immunoglobulin M / Q000032:analysis; D015212:Inflammatory Bowel Diseases / Q000276:immunology / Q000601:surgery; D007422:Intestines / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011506:Proteins / Q000032:analysis; D007507:Therapeutic Irrigation; D014867:Water / Q000032:analysis
D007070:Immunoglobulin A; D007075:Immunoglobulin M; D011506:Proteins; D014867:Water