Distinct and Non-Overlapping T Cell Receptor Repertoires Expanded by DNA Vaccination in Wild-Type and HER-2 Transgenic BALB/c Mice

Abstract

Central tolerance to tumor-associated Ags is an immune-escape mechanism that significantly limits the TCR repertoires available for tumor eradication. The repertoires expanded in wild-type BALB/c and rat-HER-2/neu (rHER-2) transgenic BALB-neuT mice following DNA immunization against rHER-2 were compared by spectratyping the variable (V)β and the joining (J)β CDR 3. Following immunization, BALB/c mice raised a strong response. Every mouse used one or more CD8+ T cell rearrangements of the Vβ9-Jβ1.2 segments characterized by distinct length of the CDR3 and specific for 63-71 or 1206-1214 rHER-2 peptides. In addition, two CD4+ T cell rearrangements recurred in >50% of mice. Instead, BALB-neuT mice displayed a limited response to rHER-2. Their repertoire is smaller and uses different rearrangements confined to CD4+ T cells. Thus, central tolerance in BALB-neuT mice acts by silencing the BALB/c mice self-reactive repertoire and reducing the size of the CD8+ T cell component. CD8+ and CD4+ T cells from both wild-type and transgenic mice home to tumors. This definition of the T cell repertoires available is critical to the designing of immunological maneuvers able to elicit an effective immune reaction against HER-2-driven carcinogenesis.

Antitumor immunization of mothers delays tumor development in cancer-prone offspring

“…We have previously identified a public TCR rearrangement, the Vb9-Jb1.2 recombination, elicited by ECTM vaccination in BALB/c mice that recognizes the p63-71 peptide with high avidity and is wiped out by central tolerance in BALB-neuT mice. 21 The expansion of this repertoire was found in all ECTM mothers as well as in 3 out of 5 neu -ECTM offspring whereas, as expected, none of the neu C ECTM offspring presented this TCR rearrangement (Fig. 5B).…”

“…On the other hand, this high-avidity CD8 C T-cell clone is deleted in BALBneuT mice because of neu expression in the thymus and its early overexpression in the mammary gland. 21 Indeed, our ECTM mothers displayed increased in vivo cytotoxic activity against splenic cells pulsed with p63-71 over control mothers (Fig. 5A).…”

“…19,20 Vaccine-elicited tumor inhibition in these mice is driven by anti-neu antibody generation, 16,17 whereas the T-cell cytotoxic response is marginal as T cells that react against neu with high affinity are wiped out by central tolerance. 21,22 The induction of high levels of antibodies following vaccination is also the mainstay of the success of maternal immunization strategy against infectious diseases. In the present study, we seek to evaluate whether maternal immunization can also induce an anti-neu immune response capable of hampering spontaneous tumor progression in BALB-neuT offspring.…”

DNA immunization using constant-current electroporation affords long-term protection from autochthonous mammary carcinomas in cancer-prone transgenic mice

“…switch to IgG2a (Figure 2b), the most effective one for antitumor activity against neu þ tumors. 15 It was previously shown 19 that effective EC-TM vaccination of BALB/c mice is able to induce a cytotoxic response against the immunodominant p185 neu (63-71) 9-mer peptide. 15 To assess whether the 0.2 A CCE condition used with EC-TM plasmids was also able to induce a cytotoxic T-cell response, BALB/c mice constant current electroporated with 50 mg of empty vector or vector coding for EC-TM plasmid were analyzed in vivo for their cytotoxic activity against syngeneic spleen cells pulsed with the immunodominant (63-71) 9-mer peptide ( Figure 3).…”

“…29 Due to rat neu transgene expression in the thymus and overexpression in the mammary gland, the T-cell repertoire of these mice is markedly affected and CD8 þ T-cell clones reacting with dominant neu epitopes are deleted. 19 Moreover, during the progression of the mammary lesions both suppressor CD4 þ CD25 þ Foxp3 þ GITR þ T-reg cells 18 and CD11b þ Gr1 þ immature myeloid cells, 30 expand. Despite the presence of these multiple negative immunological controls, a complete protection is afforded by EC-TM plasmid CCE started when mice display diffuse atypical hyperplasia and multifocal in situ carcinomas in all mammary glands and repeated every 70 days.…”