The LN compartment structure, which is destroyed during excision and transplantation, is reconstructed and repopulated with host-derived immune cells. Over the period of regeneration, donor stromal cells, the

structural components of LN, survive. Expression of cytokines, including IL-4, was found to be comparable to the expression LY294002 pattern of normal mLN; the expression of some cytokines is influenced by the area of lymphatic drainage, whereas others are LN-specific and are expressed by all mLNs, e.g. IL-2 or CCR9. Stromal cells have been shown to be involved in the regulation of immune responses by upregulation of gut-homing molecules and modulation of IgA concentration 16. Thus, stromal cells seem to powerfully influence the decision to develop Ag-induced immune responses. In order to evaluate the effect of the microenvironment and accordingly of the stromal cells

on ot, mice transplanted with pLN or mLN were analyzed with regard to delayed-type hypersensitivity (DTH) response, cell subset composition including the induction of Tregs and Selleckchem Cobimetinib cytokine and immunoglobulin production. One function of the mLN is the induction of ot. After LN regeneration, transplanted mice were fed with ovalbumin several times to induce tolerance. Tolerance induction was evaluated by the DTH response. DTH reaction has been well characterized as an influx of immune cells and resultant swelling at the Ag injection site 18, 19. Control animals fed with PBS showed a high DTH response (ear swelling) after immunization and challenge with OVA; in contrast, OVA-fed animals showed reduced ear swelling. Furthermore, mLNtx as well as pLNtx animals showed a high DTH response after PBS feeding and tolerance induction after OVA feeding. very Surprisingly, in pLNtx animals a lower DTH response was found than in mLNtx (Fig. 1). These results demonstrate that LNtx are able to induce immune tolerance. Furthermore, pLNtx animals seem to be more efficient in inducing ot than mLNtx. LNtx were analyzed after regeneration and also after tolerance induction to determine their composite cell subsets. It was found that after regeneration both LNtx showed

identical T- and B-cell as well as DC-subset compositions compared to mLN controls 16. After ot induction mLNtx still showed similar cell subsets compared to tolerized control mLN (mLN-ot), whereas pLNtx showed diminished T-cell proportions and fewer CD4+ T cells (Fig. 2A). By contrast, more B-cell percentages were identified in pLNtx animals (Fig. 2A). Only DC were found in equal percentages in all analyzed groups (Fig. 2A). In mice that received PBS instead of OVA identical cell subset patterns were observed compared to the OVA-fed groups (data not shown). After induction of an immune response by cholera toxin (CT) administration equal to DC composition, decreased T cells and increased B-cell percentages were again found in pLNtx compared to mLNtx animals (Fig. 2B).