[Determination of immunoglobulins A in the fluids of normal human intestinal perfusion]

Immunoglobulin A (IgA) in intestinal secretions is present in several molecular forms among which dimeric IgA linked to the secretory component (S-IgA) predominates. IgA was measured in jejunal perfusates obtained in nine normal subjects by intraluminal perfusion under a proximal occluding balloon of an isotonic and non antigenic solution. The method associated reverse radial immunodiffusion technique or nephelometry, using human serum as standard with chromatography on a polyacrylamide indubiose column. Chromatography separated IgA between two fractions whose elution ratios were the same as those found with mixtures of pure monomeric IgA and S-IgA. A scale was constructed from the latter, allowing the calculation of the percentages of monomeric IgA and S-IgA present in the jejunal perfusates, and that of their total content of IgA.