Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues
Reexamination Certificate
1997-07-07
2002-05-21
Spector, Lorraine (Department: 1646)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
C536S023500, C435S069700, C435S252300, C435S320100, C424S192100
Reexamination Certificate
active
06392013
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns functional protein-tyrosine kinase chimeras which are capable of redirecting immune system function. More particularly, it concerns the regulation of lymphocytes, macrophages, natural killer cells or granulocytes by the expression in said cells of chimeras which cause the cells to respond to targets recognized by the chimeras. The invention also concerns functional protein-tyrosine kinase chimeras which are capable of directing therapeutic cells to specifically recognize and destroy either cells infected with a specific infective agent, the infective agent itself, a tumor cell, or an autoimmune-generated cell. More particularly, the invention relates to the production of protein-tyrosine kinase chimeras capable of directing cytotoxic T lymphocytes to specifically recognize and lyse cells expressing HIV envelope proteins. The invention therefore provides a therapy for diseases such as AIDS (Acquired Immunodeficiency Syndrome) which are caused by the HIV virus.
BACKGROUND OF THE INVENTION
T cell recognition of antigen through the T cell receptor is the basis of a range of immunological phenomena. The T cells direct what is called cell-mediated immunity. This involves the destruction by cells of the immune system of foreign tissues or infected cells. A variety of T cells exist, including “helper” and “suppressor” cells, which modulate the immune response, and cytotoxic (or “killer”) cells, which can kill abnormal cells directly.
A T cell that recognizes and binds a unique antigen displayed on the surface of another cell becomes activated; it can then multiply, and if it is a cytotoxic cell, it can kill the bound cell.
Autoimmune disease is characterized by production of either antibodies that react with host tissue or immune effector T cells that are autoreactive. In some instances, autoantibodies may arise by a normal T- and B-cell response activated by foreign substances or organisms that contain antigens that cross react with similar compounds in body tissues. Examples of clinically relevant autoantibodies are antibodies against acetylcholine receptors in myasthenia gravis; and anti-DNA, anti-erythrocyte, and anti-platelet antibodies in systemic lupus erythematosus.
HIV and Immunopathogenesis
In 1984 HIV was shown to be the etiologic agent of AIDS. Since that time the definition of AIDS has been revised a number of times with regard to what criteria should be included in the diagnosis. However, despite the fluctuation in diagnostic parameters, the simple common denominator of AIDS is the infection with HIV and subsequent development of persistent constitutional symptoms and AIDS defining diseases such as a secondary infections, neoplasms, and neurologic disease.
Harrison's Principles of Internal Medicine,
12th ed., McGraw Hill (1991).
HIV is a human retrovirus of the lentivirus group. The four recognized human retroviruses belong to two distinct groups: the human T lymphotropic (or leukemia) retroviruses, HTLV-1 and HTLV-2, and the human immunodeficiency viruses, HIV-1 and HIV-2. The former are transforming viruses whereas the latter are cytopathic viruses.
HIV-1 has been identified as the most common cause of AIDS throughout the world. Sequence homology between HIV-2 and HIV-1 is about 40% with HIV-2 being more closely related to some members of a group of simian immunodeficiency viruses (SIV). See Curran, J. et al.,
Science,
329:1357-1359 (1985); Weiss, R. et al.,
Nature,
324:572-575 (1986).
HIV has the usual retroviral genes (env, gag, and pol) as well as six extra genes involved in the replication and other biologic activities of the virus. As stated previously, the common denominator of AIDS is a profound immunosuppression, predominantly of cell-mediated immunity. This immune suppression leads to a variety of opportunistic diseases, particularly certain infections and neoplasms.
The main cause of the immune defect in AIDS, has been identified as a quantitative and qualitative deficiency in the subset of thymus-derived (T) lymphocytes, the T4 population. This subset of cells is defined phenotypically by the presence of the CD4 surface molecule, which has been demonstrated to be the cellular receptor for HIV. Dalgleish et al.,
Nature,
312:763 (1984). Although the T4 cell is the major cell type infected with HIV, essentially any human cell that expresses the CD4 molecule on its surface is capable of binding to and being infected with HIV.
Traditionally, CD4
+
T cells have been assigned the role of helper/inducer, indicating their function in providing an activating signal to B cells, or inducing T lymphocytes bearing the reciprocal CD8 marker to become cytotoxic/suppressor cells. Reinherz and Schlossman,
Cell,
19:821-827 (1980); Goldstein et al.,
Immunol. Rev.,
68:5-42, (1982).
HIV binds specifically and with high affinity, via a stretch of amino acids in the viral envelope (gp120), to a portion of the V1 region of the CD4 molecule located near its N-terminus. Following binding, the virus fuses with the target cell membrane and is internalized. Once internalized it uses the enzyme reverse transcriptase to transcribe its genomic RNA to DNA, which is integrated into the cellular DNA where it exists for the life or the cell as a “provirus.”
The provirus may remain latent or be activated to transcribe mRNA and genomic RNA, leading to protein synthesis, assembly, new virion formation, and budding of virus from the cell surface. Although the precise mechanism by which the virus induces cell death has not been established, it is felt that the major mechanism is massive viral budding from the cell surface, leading to disruption of the plasma membrane and resulting osmotic disequilibrium.
During the course of the infection, the host organism develops antibodies against viral proteins, including the major envelope glycoproteins gp120 and gp41. Despite this humoral immunity, the disease progresses, resulting in a lethal immunosuppression characterized by multiple opportunistic infections, parasitemia, dementia and death. The failure of the host anti-viral antibodies to arrest the progression of the disease represents one of the most vexing and alarming aspects of the infection, and augurs poorly for vaccination efforts based upon conventional approaches.
Two factors may play a role in the efficacy of the humoral response to immunodeficiency viruses. First, like other RNA viruses (and like retroviruses in particular), the immunodeficiency viruses show a high mutation rate in response to host immune surveillance. Second, the envelope glycoproteins themselves are heavily glycosylated molecules presenting few epitopes suitable for high affinity antibody binding. The poorly antigenic target which the viral envelope presents, allows the host little opportunity for restricting viral infection by specific antibody production.
Cells infected by the HIV virus express the gp120glycoprotein on their surface. Gp120 mediates fusion events among CD4
+
cells via a reaction similar to that by which the virus enters the uninfected cells, leading to the formation of short-lived multinucleated giant cells. Syncytium formation is dependent on a direct interaction of the gp120 envelope glycoprotein with the CD4 protein. Dalgleish et al., supra; Klatzman, D. et al.,
Nature,
312:763 (1984); McDougal, J. S. et al.,
Science,
231:382 (1986); Sodroski, J. et al.,
Nature,
322:470 (1986); Lifson, J. D. et al.,
Nature,
323:725 (1986); Sodroski, J. et al.,
Nature,
321:412 (1986).
Evidence that the CD4-gp120 binding is responsible for viral infection of cells bearing the CD4 antigen includes the finding that a specific complex is formed between gp120 and CD4. McDougal et al., supra. Other investigators have shown that the cell lines, which were noninfective for HIV, were converted to infectable cell lines following transfection and expression of the human CD4 cDNA gene. Maddon et al.,
Cell,
46:333-348 (1986).
Therapeutic programs based on soluble CD4 as a passive agent to interfere with viral adsorption and syncytium-mediated cellu
Kolanus Waldemar
Romeo Charles
Seed Brian
Clark & Elbing LLP
O'Hara Eileen B.
Spector Lorraine
The General Hospital Corporation
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