Clinical Trial Results of a HER2/neu (E75) Vaccine to Prevent Recurrence in High-Risk Breast Cancer Patients

Purpose

E75 is an immunogenic peptide from the HER2/neu protein that is highly expressed in breast cancer. We are conducting a clinical trial of an E75 + granulocyte-macrophage colony-stimulating factor vaccine to assess safety, immunologic response, and the prevention of clinical recurrences in patients with disease-free, node-positive breast cancer (NPBC).

Patients and Methods

Fifty-three patients with NPBC were enrolled and HLA typed. HLA-A2+ patients (n = 24) were vaccinated, and HLA-A2− patients (n = 29) are observed prospectively as clinical controls. Local/systemic toxicities, immunologic responses, and time to recurrence are being measured.

Results

Only minor toxicities have occurred (one grade 3 [4%]). All patients have demonstrated clonal expansion of E75-specific CD8+T cells that lysed HER2/neu-expressing tumor cells. An optimal dosage and schedule have been established. Patients have developed delayed-type hypersensitivity reactions to E75 postvaccination compared with controls (33 v 7 mm; P < .01). HLA-A2+ patients have been found to have larger, more poorly differentiated, and more hormonally insensitive tumors compared to HLA-A2− patients. Despite this, the only two deaths have occurred in the control group. The disease-free survival in the vaccinated group is 85.7% compared to 59.8% in the controls at 22 months' median follow-up with a recurrence rate of 8% compared to 21%, respectively (P < .19). Median time to recurrence in the vaccinated patients was prolonged (11 v 8 months), and recurrence correlated with a weak delayed-type hypersensitivity response.

Conclusion

This HER2/neu (E75) vaccine is safe and effective in eliciting a peptide-specific immune response in vivo. Induced HER2/neu immunity seems to reduce the recurrence rate in patients with NPBC.

Combined clinical trial results of a HER2/neu (E75) vaccine for the prevention of recurrence in high-risk breast cancer patients: U.S. Military Cancer Institute Clinical Trials Group Study I-01 and I-02

PURPOSE

E75 is an immunogenic peptide from the HER2/neu protein, which is overexpressed in many breast cancer patients. We have conducted two overlapping E75 vaccine trials to prevent recurrence in node-positive (NP) and node-negative (NN) breast cancer patients.

EXPERIMENTAL DESIGN

E75 (HER2/neu 369-377) + granulocyte macrophage colony-stimulating factor was given intradermally to previously treated, disease-free NP breast cancer patients in a dose escalation safety trial and to NN breast cancer patients in a dose optimization study. Local and systemic toxicity was monitored. Immunologic responses were assessed using in vitro assays and in vivo delayed-type hypersensitivity responses. Clinical recurrences were documented.

RESULTS

One hundred and eighty-six patients were enrolled in the two studies (NP, 95; NN, 91). Human leucocyte antigen A2 (HLA-A2) and HLA-A3 patients were vaccinated (n = 101), whereas all others (n = 85) were followed prospectively as controls. Toxicities were minimal, and a dose-dependent immunologic response to the vaccine was shown. Planned primary analysis revealed a recurrence rate of 5.6% in vaccinated patients compared with 14.2% in the controls (P = 0.04) at a median of 20 months follow-up. As vaccine-specific immunity waned over time, the difference in recurrence lost significance at 26 months median follow-up (8.3% versus 14.8%); however, a significant difference in the pattern of recurrence persisted.

CONCLUSIONS

E75 is safe and effective in raising a dose-dependent HER2/neu immunity in HLA-A2 and HLA-A3 NP and NN breast cancer patients. More importantly, E75 may reduce recurrences in disease-free, conventionally treated, high-risk breast cancer patients. These findings warrant a prospective, randomized phase III trial of the E75 vaccine with periodic booster to prevent breast cancer recurrences.

Investigating the Combination of Trastuzumab and HER2/neu Peptide Vaccines for the Treatment of Breast Cancer

BACKGROUND

Trastuzumab, an anti-HER2/neu monoclonal antibody, is thought to promote HER2/neu receptor internalization and/or turnover. This study was designed to investigate the kinetics of trastuzumab treatment on tumor cells with varying levels of HER2/neu expression and to determine the effect of trastuzumab on HER2/neu-specific cytotoxic T lymphocyte-mediated lysis.

METHODS

Three cell lines with varying levels of HER2/neu expression were incubated with varying doses of trastuzumab at multiple time points. Trastuzumab binding and HER2/neu expression were determined. Peripheral blood mononuclear cells from three HLA-A2(+) healthy donors and four E75 peptide-vaccinated patients were stimulated with HER2/neu-derived peptides and tested in standard chromium release cytotoxicity assays with HER2/neu(+) tumor cells pretreated with trastuzumab.

RESULTS

Treatment of tumor cells with 10 microg/mL of trastuzumab in an overnight incubation resulted in saturation of cell-surface HER2/neu receptors. At higher doses, trastuzumab staining and HER2/neu expression decreased in a time-dependent manner. Pretreatment of tumor cells with trastuzumab resulted in increases in specific cytotoxicity by peptide-stimulated cytotoxic T lymphocytes from HLA-A2(+) donors over untreated cells by an average of 5.6% and 15.3% (P = .0002) for doses of 10 and 50 microg/mL, respectively. In similar experiments involving peripheral blood mononuclear cells obtained from immunized patients, the average specific cytotoxicity for untreated cells was 34.2% +/- 1.3% vs. 40.6% +/- 2.5% (P = .035) and 40.7% +/- 1.6% (P = .0005) for those treated with 10 and 50 microg/mL, respectively.

CONCLUSIONS

Our data suggest that pretreatment of breast cancer cells with trastuzumab induces turnover of the HER2/neu protein and enhanced killing by HER2/neu peptide-stimulated CTLs. This increased lysis occurs regardless of the degree of HER2/neu expression and seems more pronounced in vaccinated patients. These findings support further investigation into the use of combination immunotherapy with trastuzumab and HER2/neu peptide-based vaccines.

Evaluation of the HER2/neu-derived peptide GP2 for use in a peptide-based breast cancer vaccine trial

BACKGROUND

E75 and GP2 are human leukocyte antigen (HLA)-A2-restricted immunogenic peptides derived from the HER2/neu protein. In a E75 peptide-based vaccine trial, preexisting immunity and epitope spreading to GP2 was detected. The purpose of this study was to further investigate GP2 for potential use in vaccination strategies. Importantly, a naturally occurring polymorphism (I-->V at position 2, 2VGP2) associated with increased breast cancer risk was addressed.

METHODS

Prevaccination peripheral blood samples (PBMC) from HLA-A2 breast cancer patients and CD8+ T cells from HLA-A2 healthy donors were stimulated with autologous dendritic cells (DC) pulsed with GP2 and tested in standard cytotoxicity assays with HER2/neu+ tumor cells or GP2- or 2VGP2-loaded T2 targets. Additional cytotoxicity experiments used effectors stimulated with DC pulsed with E75, GP2, or the combination of E75+GP2.

RESULTS

GP2-stimulated prevaccination PBMC from 28 patients demonstrated killing of MCF-7, SKOV3-A2, and the HLA-A2- control target SKOV3 of 28.8+/-3.7% (P<.01), 29.5+/-4.0% (P<.01), and 16.9+/-2.7%, respectively. When compared with E75, GP2-stimulated CD8+ T cells lysed HER2/neu+ targets at 43.8+/-5.2% versus 44.2+/-5.7% for E75 (P=.87). When combined, an additive effect was noted with 58.6+/-5.4% lysis (P=.05). GP2-stimulated CD8+ T cells specifically recognized both GP2-loaded (19.6+/-5.7%) and 2VGP2-loaded T2 targets (17.7+/-5.2%).

CONCLUSIONS

GP2 is a clinically relevant HER2/neu-derived peptide with immunogenicity comparable to that of E75. Importantly, GP2-specific effectors recognize 2VGP2-expressing targets; therefore, a GP2 vaccine should be effective in patients carrying this polymorphism. GP2 may be most beneficial used in a multiepitope vaccine.

Phase I Clinical Trial of a HER-2/neu Peptide (E75) Vaccine for the Prevention of Prostate-Specific Antigen Recurrence in High-Risk Prostate Cancer Patients

PURPOSE

The E75 peptide is an immunogenic peptide from the HER-2/neu protein that is substantially expressed in prostate cancer. We are conducting a clinical trial of an E75/granulocyte macrophage colony-stimulating factor vaccine to prevent post-prostatectomy prostate-specific antigen (PSA) recurrences in high-risk prostate cancer (HRPC) patients.

EXPERIMENTAL DESIGN

Prostate cancer patients at high risk for recurrence were prospectively evaluated and identified by the validated Center for Prostate Disease Research (CPDR)/CaPSURE high-risk equation. From these high-risk equation patients, 27 HER-2/neu-expressing prostate cancer patients were enrolled. HLA-A2+ patients (n = 17) were vaccinated, whereas HLA-A2- patients (n = 10) were followed as clinical controls. Local/systemic toxicities, immunologic responses, and time to recurrence were measured.

RESULTS

This vaccine is safe with only minor toxicities observed. Additionally, the vaccine is immunogenic with all patients showing both in vivo and in vitro phenotypic and functional immune responses, although variable. HLA-A2+ patients were found to have larger tumors, higher postoperative Gleason scores, and more high-risk CPDR scores than HLA-A2- patients. Despite these differences, disease-free survival was not different between the vaccinated HLA-A2+ patients and the HLA-A2- controls at a median follow up of 23 months. Three of the four vaccinated patients that recurred had rising PSAs at the initiation of the trial. Ex vivo phenotypic assays were predictive of recurrences and correlated in general with functional assays.

CONCLUSIONS

The E75 vaccine strategy is safe and effective in eliciting an immune response against the HER-2/neu protein in HRPC patients and may be useful as a preventive strategy against disease recurrence. Vaccination in response to a rising PSA may be too late.

Evaluation of the CD107 cytotoxicity assay for the detection of cytolytic CD8+ cells recognizing HER2/neu vaccine peptides

The recently reported FACS-based CD107 assay has been used in human HIV and CMV antigen models as well as in the ex vivo analysis of tumor cytolytic T cells in a melanoma model by a single group. The purpose of our study was to validate this assay and to use it in previously untested viral and tumor antigen models. Specifically, we investigated the use of the novel CD107 cytotoxicity assay in the detection of influenza and HER2/neu tumor-specific cytolytic CD8+ T cells. CD8+ T cells from HLA-A2+ healthy donors were stimulated with autologous dendritic cells pulsed with FluM or the HER2/neu peptides, E75 or GP2. These CD8+ T cells were then tested in cytotoxicity assays at varying effector:target (E:T) ratios against T2 targets. Cytotoxicity was measured by detection of CD107a and b on the surface of CD8+ T cells. An E:T of 1:5 was found to optimize the resulting percentage of CD8+CD107+ T cells. E75- and GP2-stimulated CD8+ T cells were then tested in cytotoxicity assays with MCF-7 (HER2/neu+HLA-A2+) and AU565 (HER2/neu+HLA-A2-) tumor cells. Cytotoxicity was measured by both the CD107 assay and the (51)Cr release assay. Results of cytotoxicity were then correlated between these two assays. In representative experiments, the CD107 assay identified average specific increases for E75- and GP2-stimulated cells of 4.26 and 3.57%, respectively. These results correlated favorably with cytotoxicity as measured by the traditional (51)Cr assay. These findings confirm preliminary reports of the CD107 assay and suggest its usefulness for monitoring cancer trials.

Correlations between serum monocyte chemotactic protein-1 levels, clinical prognostic factors, and HER-2/neu vaccine-related immunity in breast cancer patients

PURPOSE

We studied serum monocyte chemotactic protein-1 (MCP-1) levels in breast cancer patients in relationship to their clinicopathologic variables and immune response to a /neu E75 vaccine.

EXPERIMENTAL DESIGN

We measured MCP-1 levels in 32 /neu(+) breast cancer patients before and after vaccination with a /neu E75 peptide + granulocyte macrophage colony-stimulating factor vaccine. Clinical prognostic variables were collected. Vaccine-specific immunologic responses were monitored.

RESULTS

Serum MCP-1 levels >250 pg/mL (MCP-high) correlated with favorable prognostic variables. MCP-high patients compared with MCP-low (<250 pg/mL) patients showed statistically significant later onset of disease, earlier stage of disease, fewer nodal metastasis, and less chemotherapy. MCP-high patients had increased levels of preexisting immunity when compared with MCP-low patients (69% versus 21%; P = 0.02). However, MCP-low patients showed higher inducible levels of MCP-1 compared with MCP-high patients (median increase, 41% versus 0%; P = 0.001) after vaccination. Moreover, MCP-low patients with >50% increase in MCP-1 levels (response-high) had worse clinical prognostic variables compared with patients with <50% increase (response-low). Response-high patients had statistically significant more poorly differentiated tumors, later stage of disease, and higher percentage of large tumors. Patients with >30% postvaccination MCP-1 increase also showed significant increases in E75-specific CD8(+) T-cells (0.05% versus 0.38%; P = 0.03) in response to vaccination.

CONCLUSIONS

High serum MCP-1 levels in breast cancer patients correlate with favorable prognostic variables and increased preexisting /neu immunity. E75 vaccination induces the largest MCP-1 response in patients with unfavorable clinicopathologic variables. Therefore, low serum MCP-1 levels may identify patients with worse prognosis and those most likely to benefit from this vaccination.

Levels of circulating regulatory CD4+CD25+ T cells are decreased in breast cancer patients after vaccination with a HER2/neu peptide (E75) and GM-CSF vaccine

PURPOSE

We are conducting clinical trials in breast cancer (BrCa) patients to test the HER2/neu peptide vaccine (E75). We have investigated the impact of this vaccine on circulating levels of regulatory T cells (Treg) and the resulting effects on antitumor responses.

EXPERIMENTAL DESIGN

Twenty-two blood samples from healthy individuals and from 22 BrCa patients including pre- and post-vaccination samples from seven vaccinated HLA-A2+ patients were stained for CD4, CD25, and CD69 as well as CD8 and E75:HLA-A2 Ig dimer and quantified by flow cytometry. Cytotoxic activity against HER2/neu+ tumors was measured by 51Cr-release. Serum from BrCa patients and normal subjects were analyzed for TGF-beta levels.

RESULTS

BrCa patients have a greater percentage of circulating Treg (CD4+CD25+, 4.45% versus 2.96%; p=0.007) than normal subjects. HLA-A2+ BrCa patients had more Treg compared to the HLA-A2- BrCa patients (CD4+CD25+, 5.63% versus 3.28%; p=0.001). E75 vaccination increased circulating activated CD4+ T cells post-vaccination (CD4+CD69+, 1.23 versus 3.81%; p=0.03). However, T(reg) were significantly reduced after vaccination (CD4+CD25+, 5.31-1.81%; p<0.0001). Furthermore, activated Treg also decreased (CD4+CD25+CD69+, 0.23% versus 0.08%; p=0.06). Importantly, post-vaccination decreases in Treg were temporally associated with increased E75 vaccine-specific CD8+ T cells and corresponding HER2/neu+ tumor cytotoxicity. Serum TGF-beta levels were significantly elevated in BrCa patients compared to normals (3548 pg/ml versus 1007 pg/ml; p=0.007). Four of seven vaccinated patients showed decreased serum TGF-beta levels post-vaccination.

CONCLUSIONS

Treg, are increased in BrCa patients along with serum levels of TGF-beta. E75 vaccination resulted in CD4+ recruitment but was associated with a significant decrease in circulating Treg and TGF-beta levels in the majority of the vaccinated patients. Successful cancer vaccination strategies may require the alteration of complex immune interactions.

Direct measurement of peptide-specific CD8+ T cells using HLA-A2:Ig dimer for monitoring the in vivo immune response to a HER2/neu vaccine in breast and prostate cancer patients

HER2/neu is a proto-oncogene and a member of the epidermal growth factor receptor family of proteins that is overexpressed in numerous types of human cancer. We are currently conducting clinical trials with the HER2/neu E75 peptide vaccine in breast and prostate cancer patients. We have evaluated the use of HLA-A2 dimer molecule for the immunological monitoring of cancer patients receiving the E75 peptide vaccine. Peripheral blood samples from patients receiving the vaccine were stained with HLA-A2 dimers containing the vaccine peptide E75 or control peptides and analyzed by flow cytometry. We compared the HLA-A2 dimer assay to standard methods of immunologic monitoring (IFN-gamma release, lymphocyte proliferation, and cytotoxicity). The HLA-A2 dimer assay was also compared with the HLA-A2 tetramer assay. E75 peptide-specific CD8 T cells were detected directly in the peripheral blood of patients by staining with E75-HLA-A2 dimers and CD8 antibodies. T cell cultures generated by repeated stimulations using E75 peptide-pulsed dendritic cells showed increased staining with E75-peptide loaded HLA-A2 dimers. Simultaneously analysis by the dimer assay and standard immunologic assays demonstrated that the dimer-staining assay correlated well with these methods of immunologic monitoring. A direct comparison using E75-specific HLA-A2 tetramers and HLA-A2 dimers for the detection of E75-specific CD8 T cells in peripheral blood showed comparable results with the two assays. Our findings indicate that the HLA-A2 dimer is a powerful new tool for directly quantifying and monitoring immune responses of antigen-specific T cells in peptide vaccine clinical trials.

Vasculitis in the Palmerston North mouse model of lupus: phenotype and cytokine production profile of infiltrating cells

OBJECTIVE

To define the phenotype of cells in the perivascular and vascular infiltrates of Palmerston North (PN) mice and the cytokines that those cells produce.

METHODS

Immunohistologic analysis, flow cytometric analysis, and reverse transcriptase-polymerase chain reaction (RT-PCR) studies were performed on tissues and cells from female PN mice and age-matched and sex-matched DBA/2 mice.

RESULTS

With aging, PN mice developed a female-predominant, lupus-like disease, with a severe systemic mononuclear cell perivasculitis and vasculitis. The perivasculitis involved arteries and veins in kidney, liver, brain, and lung; the vasculitis predominantly involved veins and venules. The perivascular and vascular infiltrates in female PN mice were composed mainly of an unusual cell type that expressed phenotypic markers characteristic of both T cells (Thy1+, CD3+, CD4+, T cell receptor + [TCR+]) and B cells (B220+). In addition, the infiltrates contained a smaller number of conventional CD4+,B220- T cells and macrophages. Very few CD8+ T cells or surface Ig+ B cells were seen. Unlike the Thy1+,B220+ T cells present in MRL/lpr mice, most of which were CD4-,CD8- and TCRalpha/beta+, the majority of the Thy1+,B220+ T cells in the perivascular/vascular infiltrates of PN mice were CD4+ and expressed either TCRalpha/beta or TCRgamma/delta. By immunohistologic staining, the cells in the perivascular and vascular infiltrates in the kidneys of older PN mice were shown to produce interleukin-4 (IL-4), IL-6, and IL-10, but not IL-2, interferon-gamma, transforming growth factor beta, tumor necrosis factor alpha, or IL-1beta. By RT-PCR, the kidneys of older PN mice were found to express high levels of IL-4, IL-6, and IL-10 messenger RNA.

CONCLUSION

The vascular and perivascular infiltrates in PN mice are composed predominantly of an unusual subpopulation of T cells that are Thy1+,B220+,CD4+,CD8-, express either TCRalpha/beta or TCRgamma/delta, and produce mainly type 2 cytokines. The exact role of these cells in the immunopathogenesis of lupus-like disease in PN mice remains to be elucidated.

Vaccination with a HER2/neu peptide induces intra- and inter-antigenic epitope spreading in patients with early stage breast cancer

BACKGROUND

We are conducting clinical vaccine trials with the HER2/neu peptide, E75, in patients with breast cancer. The purpose of this study was to demonstrate clonal expansion of E75-specific CD8(+) T cells and to identify intra- and interantigenic epitope spreading.

METHOD

Pre- and postvaccination peripheral blood leukocyte samples (24 node positive [NP] and 20 node negative [NN]) from 44 vaccinated patients were analyzed. HLA-A2:Ig dimer molecules were loaded with the HER2 peptides, E75 or GP2, and were used with anti-TcR and CD8 antibodies to stain peripheral blood leukocyte immediately ex vivo and were analyzed with flow cytometry. In 8 randomly selected patients, dimers were loaded with the folate binding protein peptide E41 to evaluate for interantigenic epitope spreading.

RESULTS

All patients with NP and 95% of the patients with NN showed E75-specific clonal expansion. Patients with NN showed more robust expansion. All patients with NP and 85% of the patients with NN showed evidence of intra-antigenic epitope that was spreading to GP2. However, patients with NN showed only moderate expansion to this subdominant epitope, which was not included in the immunizing mix. The degree of HER2/neu expression and disease stage impacted the ability to expand clonally E75- and GP2-specific CD8(+) T cells. Evidence of interantigenic epitope spreading to E41 was shown in 63% of the patients who were tested.

CONCLUSION

Our data provide evidence for the induction of intra- and interantigenic epitope spreading that results from a single HER2/neu peptide vaccine even in early staged patients. The ability to raise immunity to multiple tumor antigens depends on both the degree of HER2/neu expression and the extent of disease. Epitope spreading is an essential element for the success of a peptide vaccine strategy.

Analysis of naïve and memory CD4 and CD8 T cell populations in breast cancer patients receiving a HER2/neu peptide (E75) and GM-CSF vaccine

We are conducting clinical trials of the E75 peptide as a vaccine in breast cancer (BrCa) patients. We assessed T cell subpopulations in BrCa patients before and after E75 vaccination and compared them to healthy controls. We obtained 17 samples of blood from ten healthy individuals and samples from 22 BrCa patients prior to vaccination. We also obtained pre- and post-vaccination samples of blood from seven BrCa patients who received the E75/GM-CSF vaccine. CD4, CD8, CD45RA, CD45RO, and CCR7 antibodies were used to analyze the CD4+ and CD8+ T cells by four-color flow cytometry. Compared to healthy individuals, BrCa patients have significantly more memory and less naïve T cells and more effector-memory CD8+ and less effector CD4+ T cells. Phenotypic differences in defined circulating CD4+ and CD8+ T cell subpopulations suggest remnants of an active immune response to tumor distinguished by a predominant memory T cell response and by untapped recruitment of naïve helper and cytotoxic T cells. E75 vaccination induced recruitment of both CD4+ and CD8+ naïve T cells while memory response remained stable. Additionally, vaccination induced global activation of all T cells, with specific enhancement of effector CD4+ T cells. E75 vaccination causes activation of both memory and naïve CD4+ and CD8+ T cells, while recruiting additional naïve CD4+ and CD8+ T cells to the overall immune response.

Assessment of immunologic response and recurrence patterns among patients with clinical recurrence after vaccination with a preventive HER2/neu peptide vaccine: from US Military Cancer Institute Clinical Trials Group Study I-01 and I-02

BACKGROUND

E75, a HER2/neu immunogenic peptide, is expressed in breast cancer (BCa). We have performed clinical trials of E75 + GM-CSF vaccine in disease-free, node-positive and node-negative BCa patients at high recurrence risk and recurrences were noted in both control and vaccine groups.

METHODS

Among the 186 BCa patients enrolled, 177 completed the study. Patients were HLA typed; the HLA-A2(+)/A3(+) patients were vaccinated; HLA-A2(-)/A3(-) patients were followed as controls. Standard clinicopathological factors, immunologic response to the vaccine, and recurrences were collected and assessed.

RESULTS

The control group recurrence rate was 14.8 and 8.3% in the vaccinated group (P = 0.17). Comparing the 8 vaccinated recurrences (V-R) to the 88 vaccinated nonrecurrent patients (V-NR), the V-R group had higher nodal stage (> or = N2: 75 vs. 5%, P = 0.0001) and higher grade tumors (%grade 3: 88 vs. 31%, P = 0.003). The V-R group did not fail to respond immunologically as noted by equivalent dimer responses and post-DTH responses. Compared to control recurrent patients (C-R), V-R patients trended toward higher-grade tumors and hormone-receptor negativity. C-R patients had 50% bone-only recurrences, compared to V-R patients with no bone-only recurrences (P = 0.05). Lastly, V-R mortality rate was 12.5% compared with 41.7% for the C-R group (P = 0.3).

CONCLUSIONS

The vaccinated patients who recurred had more aggressive disease compared to V-NR patients. V-R patients had no difference in immune response to the vaccine either in vitro or in vivo. V-R patients, when compared to C-R patients, trended towards more aggressive disease, decreased recurrence rates, decreased mortality, and no bone-only recurrences.

Further characterization of the autoantibody response of Palmerston North mice

PN mice spontaneously develop, with age, a lupus-like disease. The present study further evaluated autoantibody production in female PN mice. As early as 1 month of age, all PN mice had detectable IgM antibodies to dsDNA and ssDNA and two-thirds produced IgM anticardiolipin antibodies. By 3 months of age, all PN mice exhibited evidence of isotype switch in their autoantibody response; 88-100% had serum IgG antibodies to ssDNA and dsDNA, respectively. By 6-12 months of age, essentially all female PN mice had IgG antibodies to ssDNA, dsDNA, cardiolipin and other phospholipids (PS, PC, PI, and PG), and IgG and 63% produced IgG anti-mouse erythrocyte antibodies. In addition, 50-100% produced IgA antibodies to dsDNA and ssDNA, and one-third produced IgA anti-IgG antibodies. Antibodies to U1RNP and Sm were present in 81% of 6- to 12-month-old PN mice and 39-94% had IgG or IgM antibodies to mouse thymocytes. Although all four IgG isotypes were represented in the anti-dsDNA response, IgG1 antibodies dominated the IgG anticardiolipin response. The presence of IgA autoantibodies and the predominance of IgG1 in the IgG anticardiolipin response suggest that IL-4 and either IL-5 and/or TGF-beta serve as B cell stimulatory cytokines for autoreactive B cells in PN mice.

Spontaneous formation of germinal centers in autoimmune mice

The mechanisms of autoantibody production are not well understood. Germinal centers (GC) may be important sites of immune disregulation in autoimmune diseases. In this study, we document the presence of spontaneous GC formation in the spleens of several autoimmune mouse strains that spontaneously develop autoimmune Type I diabetes and a lupus-like disease. In contrast, mouse strains that do not develop lupus did not exhibit spontaneous formation of GC. In all of the autoimmune strains studied, GC were present at 1-2 months of age, a time that closely parallels the appearance of autoantibodies. Like the GC that develop after purposeful immunization, GC in autoimmune mice contained B220(+), PNA(+), and GL-7(+) B cells, and FDC-M1(+) follicular dendritic cells. In addition, spontaneously formed GC in autoimmunity and those caused by immunization were abrogated in a similar way by a short-term treatment with anti-CD40 ligand antibody. These data indicate that spontaneously forming GC in autoimmunity are similar to those appearing after purposeful immunization.

Assessing serum cytokine profiles in breast cancer patients receiving a HER2/neu vaccine using Luminex technology

We used the Luminex assay to compare serum cytokine profiles of breast cancer patients (BCa) to healthy controls, node-positive (NP) patients to node-negative (NN), and pre- and post-vaccination serum of BCa vaccinated with a HER2/neu E75 peptide vaccine. Sera from 36 pre- and post-vaccination BCa, (12 NP and 24 NN) and 13 healthy, female donors, were evaluated using Luminex technology. Levels of 22 cytokines consisting of interleukin (IL)-1alpha, -1beta, -2, -4, -5, -6, -7, -8, -10, -12, -13, -15, -17, IFN-gamma, G-CSF, GM-CSF, TNF-alpha, IP-10, MIP-1alpha, RANTES, eotaxin and monocyte chemotactic protein-1 (MCP-1) were assessed. Six of 22 cytokines showed significant differences between BCa and healthy controls. MCP-1, eotaxin, RANTES and GM-CSF levels were significantly elevated in BCa (P<0.009) and IL-1alpha and IL-4 levels were significantly decreased in BCa (P<0.015). Cytokine levels were generally elevated in NN patients compared to NP patients with the exception of eotaxin and IL-13, which were increased in NP patients. Three cytokines, IL-6, MIP-1alpha and G-CSF reached statistical significance (P<0.05). In 34 vaccinated BCa, MCP-1, eotaxin and IL-13 were significantly elevated post-vaccination with MCP-1 demonstrating the most significant response (median, 145.8-217.0 pg/ml, P=0.003). Using a multiplex assay we found significant differences in cytokine levels in sera of BCa compared to healthy controls, in NN compared to NP patients, and in vaccinated patients. Our results support an extended analysis of serum cytokine profiles for the potential development of predictive panels in diagnosis, staging and monitoring cancer vaccine trials.