Breaking B-cell tolerance and CTL tolerance in three OVA-transgenic mouse strains expressing different levels of OVA.

It is of major importance to overcome the immunological tolerance in attempts to generate efficient tumour vaccines. Here, we describe induction of autoantibodies and self-reactive CTL in three types of OVA-transgenic mouse strains, RIP-OVA(low), RIP-mOVA and RIP-OVA(HI) exhibiting varying levels of OVA expression and tolerance. This was achieved by immunizing with DNA constructs where a foreign T-helper epitope, P30 from tetanus toxin, was inserted into the OVA sequence.

Generation of autoreactive CTL by tumour vaccines containing foreign T helper epitopes.

The aim of this study was to evaluate the effect of including a foreign T helper cell epitope in vaccines designed for generation of CTL against self-antigens and for inhibition of tumour growth. Two different vaccine designs were composed, a minimal epitope vaccine and a modified full length self-antigen, both based on OVA containing either a colinearily synthesized or an inserted Th-epitope, respectively. These vaccines were used for immunization of tolerant OVA transgenic mice (RIP-OVA(low)) and non-tolerant C57BL/6 mice.

Linked foreign T-cell help activates self-reactive CTL and inhibits tumor growth.

Transgenic mice expressing membrane-bound OVA under the rat insulin promoter, RIP-mOVA, has previously been suggested to display deletional tolerance toward the dominant CTL epitope, SIINFEKL, and provide an elegant model system to test the hypothesis that the lack of T cell help contributes to the tolerance. To understand how the CD8 tolerance is maintained in these mice, a set of neo-self-Ags, OVA, modified to contain a foreign Th peptide, were constructed and tested for their ability to induce CTL responses in RIP-mOVA mice. Immunization with these Th peptide-modified OVA molecules and not with the wild-type OVA induced self-reactive CTLs recognizing dominant CTL peptide, SIINFEKL.

Phase I study of TNFalpha AutoVaccIne in patients with metastatic cancer.

We evaluated the safety and immunogencity of a novel vaccine directed against autologous TNFalpha in a Phase I fixed dose escalation trial. The vaccine consisted of two recombinant TNFalpha proteins, with specific peptides replaced by foreign immunodominant T cell epitopes from tetanus toxoid. The main objectives were to establish a safe dose and evaluate the vaccines ability to raise neutralising TNFalpha antibodies.

Insertion of foreign T cell epitopes in human tumor necrosis factor alpha with minimal effect on protein structure and biological activity.

To create a human therapeutic vaccine able to circumvent self-tolerance against tumor necrosis factor (TNF) alpha, foreign T helper epitopes were inserted into human TNFalpha, with minimal effect on the native three-dimensional structure. TNFalpha variants were screened for solubility, structural stability, biological activity, and after immunization, for eliciting inhibitory antibodies. The longest and most flexible loop in TNFalpha, also designated loop 3, is the only region that is not involved in intra- or intermolecular interactions and therefore constitute an attractive insertion site.