Epitope spreading upon P815 tumor rejection triggered by vaccination with the single class I MHC-restricted peptide P1A.

Epitope spreading has been best characterized as an exacerbating factor in CD4(+) T cell-dependent autoimmune disease models and is believed to occur via presentation of antigens liberated by tissue destruction initiated by CD4(+) T cells specific for a primary epitope. The growing evidence that exogenous antigens can also be processed and presented by class I MHC molecules has suggested that epitope spreading could occur for CD8(+) cytotoxic T lymphocyte (CTL) responses as well. In the context of anti-tumor immunity, expansion of a CTL response to include secondary epitopes could improve the efficacy of therapeutic vaccines. To determine directly whether epitope spreading can occur during an anti-tumor immune response, two defined class I MHC-binding peptides in the P815 tumor model were utilized. We observed that immunization against the single tumor peptide, P1A, followed by rejection of a P1A(+) tumor, subsequently yielded CTL activity and tumor protection against a P1A(-) tumor variant. P1A immunized mice that subsequently rejected tumor challenge developed CTL against a second defined epitope, P1E. These results indicate that, as for class II-restricted peptides in autoimmune disease, epitope spreading can occur for class I-restricted peptides during tumor rejection. A broadened CTL response may help eliminate outgrowth of antigen-negative tumor variants.

Immunization of HLA-A2+ melanoma patients with MAGE-3 or MelanA peptide-pulsed autologous peripheral blood mononuclear cells plus recombinant human interleukin 12.

Vaccination with dendritic cells (DCs) pulsed with tumor antigen peptides has shown promise in the treatment of melanoma. Interleukin (IL)-12 production by DCs is a key component for their efficacy. Murine studies have shown that IL-12 promotes potent antitumor immunization when coadministered with peptides loaded onto other class I MHC+ cells, thus bypassing the need to use DCs. The easiest cell source to obtain in large quantity from human patients is peripheral blood mononuclear cells (PBMCs). A Phase I clinical trial was thus performed in patients with metastatic melanoma using immunization with autologous PBMCs pulsed with a MAGE-3 or a MelanA peptide, coadministered with various doses of recombinant human (rh)IL-12. Patients receiving low-to-moderate doses of rhIL-12 developed increased specific CD8+ T-cell responses. Of the eight patients showing increased immunity, six had evidence of clinical activity, with one complete, one partial, one minor, and three mixed responses observed. In two patients with mixed responses, growing tumors were found to lack expression of the antigen used to immunize. Thus, vaccination with peptide-pulsed PBMCs plus rhIL-12 induces specific immunity and has clinical activity, without the need to generate DCs. Outgrowth of antigen-negative tumors argues for the future development of polyepitope vaccines.

Antigen-specific regression of established tumors induced by active immunization with irradiated IL-12- but not B7-1-transfected tumor cells.

Transfection of modestly immunogenic tumors to express B7 family co-stimulator molecules results in their rejection by syngeneic mice, suggesting a possible clinical application in cancer patients. Immunization of naive mice with irradiated B7-1-transfected P1.HTR cells is sufficient to induce specific cytolytic T lymphocytes (CTL) and to protect against tumor challenge. However, patients to be treated will have an existing tumor burden; thus, preclinical models should examine therapeutic efficacy in an established tumor setting. Contrary to expectations, immunization of mice with irradiated B7-1-transfected P1.HTR cells had no impact on the growth of pre-established control-transfected tumors. Mice bearing control-transfected P1.HTR tumors successfully rejected living B7-1 transfectants on the contralateral flank, demonstrating the ability of tumor-bearing mice to respond to B7 co-stimulation. Inasmuch as IL-12 is another important factor for CTL maturation, P1.HTR transfectants expressing B7-1 and/or IL-12 were then constructed. Remarkably, regression of pre-established tumors was achieved following immunization with irradiated IL-12 transfectants, even without co-expression of B7-1. Rejection required a shared antigen with the tumor used for immunization, could not be reproduced with rIL-12 alone, depended on host T lymphocytes and correlated with a high IFN-gamma-producing T cell phenotype. In addition, IL-12-facilitated tumor rejection required co-operation with a CTLA-4 ligand provided by the host, and correlated with up-regulation of B7-1 and B7-2 on host antigen-presenting cells. Thus, active immunization in the established tumor setting is benefitted greatly by the provision of IL-12, which may recruit participation of sufficient B7 co-stimulation from the host that it need not be provided exogenously.

Emergency abdominal operations in the patient with acquired immunodeficiency syndrome.

BACKGROUND: We have previously shown high morbidity and mortality rates in patients with acquired immunodeficiency syndrome (AIDS) who require emergency abdominal operations. In a larger series of patients, we have investigated the reasons for these findings and have hypothesized that they are primarily the result of starvation and decreased resistance to infection. STUDY DESIGN: A retrospective review of the clinical records of patients at Montefiore Medical Center and its two associated municipal hospitals was done during a six year period. RESULTS: Postoperative morbidity and mortality rates of 50 and 38 percent, respectively, were documented and seem to be related to immunosuppression and the malnourished condition of these patients. CONCLUSIONS: Patients who meet the criteria for the diagnosis of AIDS have increased morbidity and mortality rates after emergency abdominal operations. This, however, should not exclude these patients from operation when it is indicated because many will survive and benefit from the operative procedure. Attention to nutritional support and the early diagnosis and treatment of associated infectious complications may result in decreased morbidity and mortality rates subsequent to the emergency abdominal operations.

Influence of hormones on proliferation of ER-positive cells and ER-negative cells of human breast cancer (MCF-7).

The influence of endocrine therapy on the proliferation of estrogen receptor (ER)-positive cells and ER-negative cells of human breast cancer (MFC-7) serially transplanted into nude mice was analyzed by tumor growth, dextran-coated charcoal (DCC) method, ER-immunocytochemical assay (ER-ICA) and ER-immunocytochemically stained 3H-thymidine autoradiography. In the tamoxifen (TAM) group and the medroxyprogesterone acetate (MPA) group, tumor growth was inhibited, but it was promoted in the 17-beta-estradiol dipropionate (E2) group. The ER level by the DCC method was significantly decreased in the TMA, the MPA and the E2 groups. The ER-ICA showed that the percentage of ER-positive cells was decreased in the TAM and the MPA group, but it was increased in E2 group. However, the ER-immunocytochemically stained 3H-thymidine autoradiography showed that not only the labelling index of ER-positive cells but also that of ER-negative cells was significantly decreased in the TAM and the MPA groups, while the labelling index was significantly increased in the E2 groups. Therefore, it was concluded that endocrine therapy affected the proliferation of both ER-positive cells and ER-negative cells of ER-positive breast cancer.

Breast cancer and regional lymph node dissections.

Regional lymph node metastases were evaluated in 289 patients with operable breast cancer. The metastases of the axillary and internal mammary lymph node were shown to be closely related to the survival of patients, but the status of these nodes was shown to be impossible to estimate before the operation. Thus, axillary and internal mammary node dissections seem to be very important in order to attain an acceptable amount of information for staging of certain breast cancer patients. Due to the radicality of operations including internal mammary node dissection, the use of modified extended mastectomy is proposed as the staging operation. In this manner, the anterior chest deformity created by an extended radical mastectomy can be avoided and the pectoralis major muscle spared in patients without internal mammary lymph node involvement. Also found in this study, was some evidence of the beneficial use of en bloc extended radical mastectomy for the survival of a selected group of patients.