Differential susceptibility of human Th1 versus T h 2 cells to induction of anergy and apoptosis by ECDI/antigen-coupled antigen-presenting cells

Abstract

Antigen-coupled antigen-presenting cells (APC) serve as potent tolerogens for inhibiting immune responses in vivo and in vitro, apparently by providing an antigen-specific signal through the TCR in the absence of co-stimulation. Although this approach has been well studied in rodents, little is known about its effects on human T cells. We evaluated the specificity and mechanisms of tolerization of human T cells in vitro using monocyte-enriched adherent cells that were pulsed with antigen and treated with the cross-linker, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (ECDI). Autologous antigen-coupled APC selectively tolerized T cells of the T(h)1 but not T(h)2 lineage through a mechanism that involved both antigen-specific and antigen-non-specific elements. The tolerization process was dependent on the ECDI and antigen concentration, and the coupling time, and was reflected by initial up-regulation of CD25. However, upon re-stimulation with fresh APC and antigen, tolerized T(h)1 cells failed to proliferate or to produce T(h)1 cytokine message or secreted protein, had decreased expression of CD25, CD28 and B7 and increased expression of MHC class II molecules, and demonstrated an enhanced commitment to apoptosis. T(h)1 cell tolerization could be prevented by adding anti-CD28 antibody, IL-2 or untreated APC at the same time as the ECDI/antigen-coupled APC, or reversed by adding anti-CD28 antibody or IL-2 upon re-stimulation with fresh APC plus antigen. Thus, the tolerizing effect of ECDI/antigen-coupled APC on human T(h)1 cells appears to involve a reversible anergy mechanism leading to apoptosis, whereby the targeted T cells receive full or partial activation through the TCR, without coordinate co-stimulation. These data suggest dichotomous signaling requirements for inactivating cells of the T(h)1 and T(h)2 lineages that may have important implications for treatment of T(h)1-mediated autoimmune or inflammatory diseases.

Peripheral Tolerance Induction Using Ethylenecarbodiimide-Fixed APCs Uses both Direct and Indirect Mechanisms of Antigen Presentation for Prevention of Experimental Autoimmune Encephalomyelitis

“…For example, low B7 expression on the donor-coupled cells is necessary for tolerance induction, while CTLA-4 is important for the maintenance phase of Ag-SP tolerance upon secondary encounter with Ag on stimulatory APCs expressing up-regulated levels of costimulatory molecules (14,15,24). Also, we have demonstrated that a chemical fixative, such as ECDI, is required during the coupling process (24,25). Taken together, these observations support the idea that i.v.…”

Spontaneous Development of a Pancreatic Exocrine Disease in CD28-Deficient NOD Mice

“…For this study, our approach was modeled after the insulin-coupled spleen cell tolerance method used to prevent T1D (40). This therapy has direct clinical applications for the treatment of AIP since coupled-cell tolerance has already been used successfully to tolerize Ag-specific human T cell responses (65). The tolerization protocol was successful in limiting the degree of mononuclear cell infiltration into the exocrine pancreas in comparison to SHAM-treated NOD.CD28KO recipient mice.…”

High Dose Allergen Stimulation of T Cells from House Dust Mite-Allergic Subjects Induces Expansion of IFN-γ+ T Cells, Apoptosis of CD4+IL-4+ T Cells and T Cell Anergy

“…As apoptosis can follow anergy induction after high dose antigen treatment [37], deletion of allergen-specific Th cells could also lead to in part the reduced proliferative responses seen in our cultures stimulated with high HDM extract concentration. Furthermore, preferential deletion of IL-4- and IL-5-producing T cells could contribute to the shift towards dominant T cell IFN-γ cytokine production.…”