Vaccination for melanoma.

Our knowledge of the immune system has grown tremendously in the 50 years since Coley used bacteria in an attempt to create a vaccine for cancer. The strategy for cancer vaccines has developed in that time as well. Both clinical and laboratory evidence suggests that melanoma is the more immunogenic of solid tumors. If treated early, melanoma can be controlled with surgery, but many patients continue to die from it. With our increased understanding of the immune system's interaction with melanoma, many clinical trials of melanoma vaccines are now underway. Vaccines designed to treat metastatic melanoma have shown some evidence of clinical effectiveness. This article outlines the current status of melanoma vaccination.

Pseudomonas exotoxin-mediated delivery of exogenous antigens to MHC class I and class II processing pathways.

Peptides associated with class II MHC molecules are normally derived from exogenous proteins, whereas class I MHC molecules normally associate with peptides from endogenous proteins. We have studied the ability of Pseudomonas exotoxin A (PE) fusion proteins to deliver exogenously added antigen for presentation by both MHC class I and class II molecules. A MHC class II-restricted antigen was fused to PE; this molecule was processed in a manner typical for class II-associated antigens. However, a MHC class I-restricted peptide fused to PE was processed by a mechanism independent of proteasomes. Furthermore, we also found that the PE fusion protein was much more stable in normal human plasma than the corresponding synthetic peptide. We believe that effective delivery of an antigen to both the MHC class I and class II pathways, in addition to the increased resistance to proteolysis in plasma, will be important for immunization.

Melanoma vaccines.

Remarkable advances in tumor vaccination have been made since Coley first deliberately infected cancer patients with both live and heat-killed bacteria. Melanoma is the most immunogenic solid tumor and, as such, has served as the major model for tumor vaccine investigation in both the laboratory and the clinic. Many advances in the field of melanoma vaccination have been based on an improved understanding of the cellular interaction required to induce a specific antitumor immune response. As a result of this new knowledge, many clinical trials of melanoma vaccines are now under way, and vaccines for metastatic melanoma have shown evidence of clinical effectiveness. This paper outlines the current status of melanoma vaccination.

Melanomas with concordant loss of multiple melanocytic differentiation proteins: immune escape that may be overcome by targeting unique or undefined antigens.

Melanoma-reactive HLA-A x 0201-restricted cytotoxic T lymphocyte (CTL) lines generated in vitro lyse autologous and HLA-matched allogeneic melanoma cells and recognize multiple shared peptide antigens from tyrosinase, MART-1, and Pme117/gp100. However, a subset of melanomas fail to be lysed by these T cells. In the present report, four different HLA-A x 0201+ melanoma cell lines not lysed by melanoma-reactive allogeneic CTL have been evaluated in detail. All four are deficient in expression of the melanocytic differentiation proteins (MDP) tyrosinase, Pme117/gp100, gp75/ trp-1, and MART-1/Melan-A. This concordant loss of multiple MDP explains their resistance to lysis by melanoma-reactive allogeneic CTL and confirms that a subset of melanomas may be resistant to tumor vaccines directed against multiple MDP-derived epitopes. All four melanoma lines expressed normal levels of HLAA x 0201, and all were susceptible to lysis by xenoreactive-peptide-dependent HLA-A x 0201-specific CTL clones, indicating that none had identifiable defects in antigen-processing pathways. Despite the lack of shared MDP-derived antigens, one of these MDP-negative melanomas, DM331, stimulated an effective autologous CTL response in vitro, which was restricted to autologous tumor reactivity. MHC-associated peptides isolated by immunoaffinity chromatography from HLA-A1 and HLA-A2 molecules of DM331 tumor cells included at least three peptide epitopes recognized by DM331 CTL and restricted by HLA-A1 or by HLA-A x 0201. Recognition of these CTL epitopes cannot be explained by defined, shared melanoma antigens; instead, unique or undefined antigens must be responsible for the autologous-cell-specific anti-melanoma response. These findings suggest that immunotherapy directed against shared melanoma antigens should be supplemented with immunotherapy directed against unique antigens or other undefined antigens, especially in patients whose tumors do not express MDP.

Terminal modifications inhibit proteolytic degradation of an immunogenic MART-1(27-35) peptide: implications for peptide vaccines.

Peptide epitopes for tumor-reactive cytotoxic T-lymphocytes (CTL) have been identified on human cancers and are being used in tumor vaccine trials. However, the pharmacokinetics and pharmacodynamics of such peptides have been inadequately studied. It is predicted that immunogenic tumor peptides would have short half-lives in vivo. The goal of the present work was to evaluate the stability of the immunogenic peptide MART-1(27-35) in fresh normal human plasma (NHP) and to identify modifications that convey protection against enzymatic destruction without loss of immunogenicity. We evaluated the stability of the MART-1(27-35) peptide (AAGIGILTV) and modified forms of that peptide for stability and immune recognition in an in vitro model. The peptides were incubated in plasma for varied time intervals and evaluated for their ability to reconstitute the epitope for MART-1(27-35)-reactive CTL. Loss of CTL reactivity signaled loss of immunoreactive peptide. When 1 microM MART-1(27-35) peptide was incubated in plasma prior to pulsing on target cells, CTL reactivity was lost within 3 hr, and the calculated half-life of this peptide was 22 sec. This degradation was mediated by peptidases. The stability of MART-1(27-35) was markedly prolonged by C-terminal amidation and/or N-terminal acetylation (peptide capping), or by polyethylene-glycol modification (PEGylation) of the C-terminus. These modified peptides were recognized by CTL. The MART-1(27-35) peptide is very unstable in plasma. It is probable that it and other immunogenic peptides will be similarly unstable in vivo. Immunogenicity of these peptides might be enhanced by creating modifications that enhance stability.

Activated alpha 2-macroglobulin reverses the immunosuppressive activity in human breast cancer cell-conditioned medium by selectively neutralizing transforming growth factor-beta in the presence of interleukin-2.

The immunosuppressive activity of tumor cells may be mediated by tumor-derived cytokines such as transforming growth factor-beta (TGF-beta) and interleukin-10 (IL-10). A human breast cancer cell line derived from malignant ascites (BRC 173) secreted TGF-beta, but not IL-10, into tissue culture supernatant (TCS). BRC 173 TCS suppressed natural killer (NK) and lymphokine-activated killer (LAK) cell activity and also blocked the generation of HLA-A*0201-restricted tumor-reactive cytotoxic T-lymphocyte (CTL) lines in vitro. Human alpha 2-macroglobulin (alpha 2M), a plasma protein and cytokine carrier that binds isoforms in the TGF-beta family, was tested for its ability to neutralize the immunosuppressive activity in BRC 173 TCS. alpha 2M was converted to its activated conformation by reaction with methylamine (alpha 2M-MA) and then incubated with normal human peripheral blood lymphocytes (PBL) in the presence of IL-2 and BRC 173 TCS. Lysis of NK targets (K562) and LAK cell targets (DM6 melanoma) by the PBL was examined after 6 days of culture. PBL cultured in IL-2, without TCS or alpha 2M-MA, were lytic for both target cells. BRC 173 TCS substantially suppressed the lytic activity of the PBL in the presence of IL-2. When TGF-beta-neutralizing antibody was added to the PBL culture medium with IL-2 and TCS, a majority of the lytic activity was restored. alpha 2M-MA (280 nM) neutralized almost all of the immunosuppressive activity in the TCS, restoring 80-100% of the lytic activity without any apparent effect on the activity of IL-2. The ability of alpha 2M-MA to counteract immunosuppressive cytokines in breast cancer TCS was evident in serum-containing and serum-free medium. These studies demonstrate the activated alpha 2M can function as a selective cytokine neutralizer to thereby promote the activation of NK, LAK, and tumor-specific CTL responses.

Making the transition to higher education: opportunities for student empowerment.

This article focuses on the transition process for high school students with learning disabilities as they move from secondary to postsecondary settings. The role of the student will be examined as it relates to the transition process, including participating in the transition planning team, selecting high school classes, searching for the best postsecondary option, and enrolling in either a 2- or 4-year college. By being actively involved in the transition process from the beginning, students can become informed consumers about their options and rights under law. Practical suggestions for high school service providers, teachers, and parents are included as they relate to supporting students in this process.

Operationalizing a definition of learning disabilities.

Past, present, and future concerns regarding the definition of learning disabilities (LD) are documented. Research on efforts to clarify the LD label is discussed, with a focus on the questionable utility of the discrepancy model. Finally, an approach to operationalizing the NJCLD definition of LD is presented and applied.

Promoting access, accommodations, and independence for college students with learning disabilities.

This article focuses on the four primary issues that directly affect service delivery to students with learning disabilities in postsecondary settings, including (a) How are high school and post-secondary settings different? (b) How are eligibility and access determined? (c) How are reasonable accommodations determined? and (d) How can the independence level of college students with learning disabilities be fostered? Each of these issues will be discussed within the context of the student's transition from high school, where Public Law 94-142 is in effect, to college, where Section 504 of the Rehabilitation Act of 1973 applies.