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-γ and interleukin-2. However, co-culture experiments (IEL + LPMNC) have shown that IEL can enhance the PHA-induced synthesis of IL-2 and interferon-γ, but not IL-10 by LPMNC. Using a transwell filter culture system apparatus, this effect was shown not to require a cell-to-cell interaction. Thus, IEL in vitro may modulate the cytokine synthesis of LPMNC, through the production of soluble factors. This may prove highly relevant in the in vivo immune activation of the gastrointestinal mucosa

IgA in the horse: cloning of equine polymeric Ig receptor and J chain and characterization of recombinant forms of equine IgA

As in other mammals, immunoglobulin A (IgA) in the horse has a key role in immune defense. To better dissect equine IgA function, we isolated complementary DNA (cDNA) clones for equine J chain and polymeric Ig receptor (pIgR). When coexpressed with equine IgA, equine J chain promoted efficient IgA polymerization. A truncated version of equine pIgR, equivalent to secretory component, bound with nanomolar affinity to recombinant equine and human dimeric IgA but not with monomeric IgA from either species. Searches of the equine genome localized equine J chain and pIgR to chromosomes 3 and 5, respectively, with J chain and pIgR coding sequence distributed across 4 and 11 exons, respectively. Comparisons of transcriptional regulatory sequences suggest that horse and human pIgR expression is controlled through common regulatory mechanisms that are less conserved in rodents. These studies pave the way for full dissection of equine IgA function and open up possibilities for immune-based treatment of equine diseases

Induction of rat secretory IgA antibodies against cholera toxin by a synthetic peptide.

There is accumulating evidence concerning the possible importance of secretory IgA antibodies in defence mechanisms against infections of the gastrointestinal tract, including cholera. Intestinal IgA antibodies are also thought to play a major role in protection against the diarrhoeogenic effects of cholera toxin. We therefore attempted to induce secretory IgA antibodies towards a reactive synthetic peptide from the cholera toxin B subunit sequence. We report that rat biliary secretory IgA antibodies against the CTP3 peptide (residues 50-64 of the B subunit) were obtained by three intra-Peyer's patch immunizations, at 2-week intervals, with CTP3 conjugated to tetanus toxoid in complete Freund's adjuvant. Purified secretory IgA fractions from bile of such immunized rats reacted with the carrier toxoid, but also with the CTP3 peptide, and with the native cholera toxin, they also partially neutralized its biological activity, as assayed by inhibition of in vitro cholera toxin-induced cAMP production in mouse thymocytes