Induction of antigen specific CD4+ T cell responses by invariant chain based DNA vaccines

In this report, the use of DNA vaccination to induce class II restricted antigen specific proliferative responses was studied. To this end, a construct encoding the invariant chain (Ii) was engineered in which the Class II associated invariant chain peptide (CLIP) sequence was replaced by an immunogenic epitope derived form Heat Shock Protein 60, HSP60 178-186. Transfection studies in vitro showed that this construct can be used to efficiently load MHC class II molecules and present epitopes to MHC class II restricted antigen specific T cells. In addition, we showed that intradermal immunisation of Lewis rats with these constructs induced antigen specific T cells in vivo. Therefore, our Ii-gene constructs can be used to immunise for defined CD4+ T cell epitope sequences.

Nasal application of a naturally processed and presented T cell epitope derived from TCR AV11 protects against adjuvant arthritis

Reactivity towards TCR peptides plays an important role in the regulation of several experimental autoimmune diseases. In a previous paper, we showed the TCRAV11 usage by an arthritogenic T cell clone isolated from a rat with adjuvant arthritis (AA). Moreover, we identified three immunogenic peptides in AV11: AV11 24-40, 41-55 and 66-80. In the present study, we show that T cells directed towards all three epitopes are part of the immune repertoire. The strongest delayed-type hypersensitivity (DTH) reaction was observed against the peptide derived from the third framework region, peptide AV11 66-80. DTH reactions to this peptide were detectable in naive rats and increased significantly after AA induction. Interestingly, modulation of the AV11 66-80 T cell response by nasal AV11 66-80 administration resulted in reduced DTH responses and in a strong inhibition of AA. These findings suggest that during the natural course of AA, T cells directed towards the third framework region of AV11 do not have a disease regulatory function, but instead play a role in the deterioration of AA.

Induction of experimental autoimmune arthritis by a public epitope of the T cell receptor variable alpha domain of an arthritogenic T cell clone

T cell receptor (TCR) peptide immunizations have been demonstrated to protect against experimental autoimmune diseases. These findings have led to clinical trials employing TCR peptides in multiple sclerosis and rheumatoid arthritis patients. Previously, we identified a strongly immunogenic region of the TCR alpha chain of an arthritogenic T cell clone (AV11 66-80). In this report, we show that rats immunized with AV11 66-80 developed arthritis with clinical symptoms and histology similar to adjuvant arthritis (AA). Transfer of this disease into naive rats using AV11 66-80-specific T cells proved the T cell-mediated character of the disease. The AV11 66-80 arthritic rats developed resistance to Mycobacterium tuberculosis-induced AA, indicating that both forms of arthritis depended on similar regulatory mechanisms. This first demonstration of TCR peptide-induced arthritis, together with an earlier report on a polymorphism in this very same AV11 66-80 region involved in arthritis resistance in mice, suggests a central role of the public epitope AV11 66-80 in the control of autoimmune arthritis. Although TCR peptide immunizations can be exploited to prevent experimental autoimmunity, caution should be taken in the induction of TCR peptide-specific T cells for immunotherapy to avoid adverse effects as shown here.

Generation and characterization of a clonotypic antibody specific for the T cell receptor of an arthritogenic T cell clone--studies in adjuvant arthritis

Adjuvant Arthritis (AA) can be induced by passive transfer of a T cell clone (A2b) derived from arthritic rats, specific for Heat Shock Protein 60, HSP60 176-190. Furthermore, a crucial role for T cells with HSP60 176-190 specificity in AA was shown by induction of tolerance using HSP60 176-190 or by immunization with an altered peptide ligand based on the same sequence. To study clonal expansion of A2b-like T cells during AA and to determine their role in AA induction, we generated a clonotypic antibody, 16C4, specific for the TCR of the A2b T cell clone (TCR AV11S1/BV18). This antibody stained A2b T cells in flow cytometry experiments, induced proliferation of A2b cells when fixed on a solid support, and inhibited antigen-induced A2b proliferation when added in solution. A2b-like T cells were detected in a low frequency in lymphoid organs of arthritic rats. Thus, as in vivo administration of 16C4 did not inhibit AA, cells containing the determinant recognized by 16C4 are possibly not the sole contributors to AA development. Furthermore, epitope specific interventions by antigen administration may be possible even in cases where the epitope specific T cell clonotype is of low frequency.

FSHD associated DNA rearrangements are due to deletions of integral copies of a 3.2 kb tandemly repeated unit

Facioscapulohumeral muscular dystrophy (FSHD) is a neuromuscular disorder characterized by progressive weakness of the facial, shoulder and upper arm muscles. The disease is associated with DNA rearrangements which are detectable using probe p13E-11 (D4F104S1) in DNA digested with EcoRI or other restriction enzymes. We have cloned and characterized the rearranged EcoRI fragment of four unrelated FSHD patients. Restriction fragment mapping and DNA sequence analysis showed that the proximal and distal parts of the EcoRI fragment, which flank a region of tandemly repeated 3.2 kb units, are identical in normal and rearranged EcoRI fragments. These results strongly support the hypothesis that the FSHD associated rearrangements are due to deletions of integral copies of the 3.2 kb repeated unit. Since these repeated units are likely to form part of the FSHD transcription unit, the variation in repeat unit number might affect the function of the gene product. Hence, our data confine the FSHD gene region and thus provide a starting point for cloning the FSHD gene.