Efficient Delivery of T Cell Epitopes to APC by Use of MHC Class II-Specific Troybodies

Abstract

A major objective in vaccine development is the design of reagents that give strong, specific T cell responses. We have constructed a series of rAb with specificity for MHC class II (I-E). Each has one of four different class II-restricted T cell epitopes genetically introduced into the first C domain of the H chain. These four epitopes are: 91–101 λ2315, which is presented by I-Ed; 110–120 hemagglutinin (I-Ed); 323–339 OVA (I-Ad); and 46–61 hen egg lysozyme (I-Ak). We denote such APC-specific, epitope-containing Ab “Troybodies.” When mixed with APC, all four class II-specific Troybodies were ∼1,000 times more efficient at inducing specific T cell activation in vitro compared with nontargeting peptide Ab. Furthermore, they were 1,000–10,000 times more efficient than synthetic peptide or native protein. Conventional intracellular processing of the Troybodies was required to load the epitopes onto MHC class II. Different types of professional APC, such as purified B cells, dendritic cells, and macrophages, were equally efficient at processing and presenting the Troybodies. In vivo, class II-specific Troybodies were at least 100 times more efficient at targeting APC and activating TCR-transgenic T cells than were the nontargeting peptide Ab. Furthermore, they were 100–100,000 times more efficient than synthetic peptide or native protein. The study shows that class II-specific Troybodies can deliver a variety of T cell epitopes to professional APC for efficient presentation, in vitro as well as in vivo. Thus, Troybodies may be useful as tools in vaccine development.

Induction of central T cell tolerance: Recombinant antibodies deliver peptides for deletion of antigen-specific CD4+8+ thymocytes

“…T cells in draining lymph nodes of reconstituted BALB/c mice [25]. Consistent with this, we here show that i.v.…”

“…Troybodies have proven highly efficient, compared to synthetic peptides, at eliciting T cell responses in vitro and in vivo [23][24][25]. By constructing Troybodies that target thymic APC for efficient delivery of self-T cell epitopes, thymocytes with damaging selfspecificities could possibly be more efficiently deleted.…”

Antibody‐mediated delivery of antigen to chemokine receptors on antigen‐presenting cells results in enhanced CD4+ T cell responses

“…Previous reports have established that Ab must be internalized and processed before Ab-derived peptides can be presented [4][5][6]17]. Indeed, we demonstrate that T cell activation was abolished if the APC were treated with leupeptin or brefeldin A prior to incubation with CCR1-specific mAb.…”

“…The latter strategy has the advantage that it maintains Ig structure and in vivo stability (K. W. Schjetne, unpublished). Ab with T cell epitopes introduced into loops in their C-region can be equipped with V-regions specific for APC [17,27] and have been termed Troybodies. Based on the present results, Troybodies with cloned chemokine receptorspecific V-regions and with T cell epitopes in their C-regions could be a promising strategy for vaccination purposes.…”

Preferential Induction of CD4+ T Cell Responses through In Vivo Targeting of Antigen to Dendritic Cell-Associated C-Type Lectin-1

“…One of these is vaccination, the efficiency of which can be enhanced by optimizing Ag delivery to DCs. This can be done by using Abs specific for DC-expressed molecules as in vivo Ag carriers; using such an approach, a lowered requirement for Ag dose in stimulating immune responses in mice has been observed after targeting a variety of molecules, including MHC class II, CD11c, CD205, CD80/86, F4/80-like receptor (FIRE), CIRE, and the undefined Ag recognized by the mAb 33D1 (1)(2)(3)(4)(5)(6)(7)(8)(9). In addition, in vitro studies have shown that Abs specific for the mannose receptor or DC-SIGN can effectively deliver Ag to human DCs, indicating that this strategy will also be applicable to human vaccination (10,11).…”