Human colonic intraepithelial lymphocytes regulate the cytokines produced by lamina propria mononuclear cells.

Using an in vitro autologous human system, the immunomodulatory function of colonic intraepithelial lymphocytes (IEL) on cytokine production by lamina propria mononuclear cells (LPMNC) has been investigated. In contrast to LPMNC, colonic IEL produced only low amounts of IL-10, interferon-gamma and interleukin-2. However, co-culture experiments (IEL + LPMNC) have shown that IEL can enhance the PHA-induced synthesis of IL-2 and interferon-gamma, but not IL-10 by LPMNC.

Effects of intrajejunal perfusion and chronic ingestion of Lactobacillus johnsonii strain La1 on serum concentrations and jejunal secretions of immunoglobulins and serum proteins in healthy humans.

Objectives: Link-Amster reported an increase in serum IgA when healthy subjects ingested a fermented dairy product containing Lactobacillus johnsonii La1. We aimed to assess the effects of La1 on the jejunal secretions and serum concentrations of total and specific immunoglobulins and proteins.

Methods: Twelve healthy volunteers ingested a fermented milk containing La1 or a control from day 1 till day 28, following a randomised double blind protocol.

Secretion of immunoglobulins and plasma proteins from the colonic mucosa: an in vivo study in man.

There are no available data on immunoglobulins and albumin outputs into the normal human colon. We thus measured the intracolonic secretion rates of IgA, IgG, IgM, secretory component (SC) and plasma proteins (albumin (Alb), orosomucoid (Oro), transferrin (Transf) and alpha 2-macroglobulin (alpha 2-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 alpha 2-M were measured in the rectal effluents by immunoradiometric assay.

Validation of IgA1 and IgA2 measurements by a solid-phase immunoradiometric assay in serum and secretions.

We describe specific, sensitive and reproducible immunoradiometric assays to measure total IgA and IgA subclass levels in biological fluids, which take into account the problem that polymeric forms are differently recognized in immunoassays. Sera from subjects totally deficient in one of the IgA subclasses allowed us to ensure the specificity of the subclass assays and to define the proportions of IgA1 (84%) and IgA2 (16%) in the normal pooled serum (from 30 blood donors) used as standard. With purified milk 11-S secretory IgA1 and 11-S secretory IgA2, we determined a correction factor for the corresponding polymeric forms using, respectively, monomeric IgA1 and monomeric IgA2 from pooled serum as standards.