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The aim of this work was to study the jejunal secretion of immunoglobulins (Ig), albumin, and hyaluronan in response to jejunal perfusion of an elemental diet. A four lumen tube with a proximal occluding balloon at the angle of Treitz was used for jejunal perfusion in seven healthy volunteers (mean age 23 years). The length of the test segment was 40 cm. The jejunum was successively perfused with a control electrolyte solution for 80 minutes and with an elemental diet (containing 20.5 milligrams of free amino acids and 104.2 milligrams of oligosaccharides) for 100 minutes. The jejunal fluid concentrations of albumin, IgG, monomeric IgA (m-IgA), polymeric IgA (p-IgA), IgM, secretory component, and hyaluronan were measured and their jejunal outputs calculated. Within 20 minutes of starting perfusion with the elemental diet there was a significant increase in the secretion rates of albumin (x3.3), IgG (x5), M-IgA (x3.7), p-IgA (x2), IgM (x2), and secretory component (x1.6), but the hyaluronan secretion rate was not changed. The increase in m-IgA, p-IgA, IgM, and secretory component output suggests that intestinal perfusion of an elemental diet results in stimulation of secretory immunity. The increase in albumin and IgG output probably reflects a nutrient induced leakage from the plasma compartment.

SUMMARYThere are no available data on immunoglobulins and albumin outputs into the nonnal human colon. We thus measured the intracolonic secretion rales of IgA, IgC IgM. secretory component {SC) and plasma proteins (albumin (Alb), orosomucoid (Oro). transferrin (TransQ and o;;-macrog!obulin (o^-M)). Using a pancolonic perfusion technique in 10 healthy volunteers (six females, four males, mean age 24 years), concentrations and outputs of Alb. immunoglobulins, SC, Oro, Transf and Q2-M were measured in the rectal effluents by immunoradiometric assay. Monomeric (m) and polymeric (p) IgA distribution was analysed by sucrose density ultracentrifugation. The secretion of polymeric IgA (p-lgA) was I53;ig/min. i.e. 220mg/day. exceeding that of other immunoglobulins (m-IgA 8-5/(g/min; IgG 33-5/ig/min; IgM 17/tg/min) and of non-immunoglobulin proteins (Alb 104;/g/min;Oro9/ig/min; Transf 7/jg/min; CH-M 4-5/ig/min). p-IgA was entirely linked to SC (secretory IgA) and 12% of SC was in free form. About 62% of total IgA was IgA2. For each protein, a relative coefficient of excretion (RCE) was calculated (colon to serum concentration ratio expressed relative to that of Alb). The p-IgA, IgM and m-IgA RCE were 277. 6 and 2 2 times higher than the values predicted from their molecular weight. RCE of non-immunoglobulin proteins also exceeded the values expected from a passive seepage from the vascular compartment. The intracolonic clearance of Alb extrapolated to 24 h was only 3-7 ml/day. These results show the high local production and/or the facilitated transport to the colonic lumen of p-IgA, and are in very good agreement with the distribution of plasma cells in the colonic mucosa.Keywords colonic perfusion immunoglobulins immunoglobulin A mucosal immunology secretory component

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