Antigens tumor-specific

The list of MoAb or fusion proteins used in treatment of every type of cancer is continually growing as research identifies more cancer-associated antigens. MoAb targeting a tumor-specific antigen is used... 

Inadequate performance may result from lack of antigen specificity, e.g., tumor-specific antigens are often differentiation antigens which also occur, although in a lower density on nontarget cells (Poste, 1984). 

Schroit, A. J., and Key, M. E. (1983). Induction of syngeneic tumor-specific immunity by liposomes reconstituted with L2C tumor-cell antigens, Immunology. 49. 431-438. 

Tumor Vaccines. Autologous or allogenic tumor cells which are administered as vaccine (e.g., tumor cell lines tumor cell lysates primary explant). This group also includes autologous antigen presenting cells pulsed with tumor specific peptides or tumor cell lysates. 

In addition to having an overabundance of several self-antigens, tumor cells express unique antigens, which can be recognized by the host immune system, provided that the immune system is simultaneously activated. Without this activation, the immune system will become tolerized to the unique antigens known as tumor-associated antigens (TAAs), which are usually small peptides of 8 to 10 amino acids. The potential exists for the eradication of cancers by injection of TAAs and the subsequent immune response. Indeed, there have been many tumor-reactive CTLs identified that recognize specific TAAs (15). 

Most antibodies available are reactive with the core protein. The abnormal or decreased glycosylations characteristically seen in tumors unmasks epitopes on the core protein, giving rise to heterogeneous reactivity with different antibodies. To date, none of the antibodies directed to these antigens are specific for tumors or epithelial tumors of particular sites. 

Lou, Y., Vitalis, T. Z., Basha, G., Cai, B., Chen, S. S., Choi, K. B., Jeffries, A. P., Elliott, W. M., Atkins, D., Seliger, B., and Jefferies, W. A., 2005, Restoration of the expression of transporters associated with antigen processing in lung carcinoma increases tumor-specific immune responses and survival, Cancer Res. 65 7926-7933. 

As a result, we started to study the mode of reaction of atypical elements with certain monoclonal antibodies binding to individual antigens, tumor markers specific for the respective cellular populations. Moreover, the method can be used to determine the degree of their maturity, presence of individual receptors, and the state of activation in the course of their cellular cycle. 

Several plant viral vectors have been used to successfully produce vaccines and therapeutic proteins in plants. TMV-based expression vectors represent one of the more successful examples and have produced a wide array of therapeutic proteins such as a-trichosanthin, tumor-specific single-chain antibodies, and a number of vaccine antigens (Table 4.1) (Dalsgaard et al., 1997). More recent examples of plant viral expression vectors utilized for vaccine production are provided in detail in Koprowski and Yusibov (2001), Pogue et al. (2002), and Canizares et al. (2005). 

There is a perceived need to develop effective vaccines against bovine spongiform encephalopathy (BSE) and the human form, new variant Creutzfeldt-Jacob (nvCJ) disease. Organ transplant vaccines would obviously be beneficial and tetanus toxoid has been shown to lower cholesterol in animals. Tumor-specific antigens have also been explored and heat stress proteins have been evaluated as adjuvants in this case. 

Gold P, Freedman SO, Demonstration of tumor-specific antigens in human colonic carcinomata by immunological tolerance and absorption techniques, Journal of Experimental Medicine, 122 467-481, 1965. 

Activation and differentiation of cytotoxic T lymphocytes (CD8+ T cells) (CTLs) require interplay of various cytokines and cells. During the presentation of tumor-specific antigens by antigen-presenting cells (APCs) to helper T cells (CD4+ T cells), cytokines present in the microenvironment control the helper immune response to develop into either a cellular or a humoral response. CD4+ T cells have been classified into Thl and Th2 subsets according to the pattern of cytokines they produce. Thl clones secrete IL-12 and IFN-y, whereas Th2 clones secrete IL-4, IL-5, IL-6 and IL-10. Thl immune response is beneficial for the development of the cellular cytotoxic (CD8) immune response, whereas Th2 immune response is inhibitory to cytotoxic response. IFN-y is a type 1 interferon that also promotes Thl-type anti-tumor immunity, reduces tumor cell growth, and inhibits angiogenesis. 

Peterson, J. A., J. R. Couto, M. R. Taylor and R. L. Ceriani (1995). Selection of tumor-specific epitopes on target antigens for radioimmunotherapy of breast cancer. Cancer Res 55(23 Suppl) 5847s-5851s. 

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