An Overview of Immunology - Systemic Review
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Original Article An Overview of Immunology - Systemic Review P. Parveen1, P.Usha1, Ch.Sowjanya1, S.V.R.L.Sravika1, Bhavana Ragala1, and M. Gayatri Ramya2* 1Hindu College of Pharmacy Amaravathi Road, Guntur-522002 India. 2Acharya Nagarjuna University, University college of Pharmaceutical Sciences, Nagarjuna Nagar, Guntur-522510 India. ABSTRACT Immunology is one of the most rapidly developing areas of medical biotechnology research and has great promises with regard to the prevention and treatment of a wide range of disorders such as the inflammatory diseases. In addition, infectious diseases are now primarily considered immunological disorders, while neoplastic diseases and organ transplantation and several autoimmune diseases are involved in an immunosuppressive state. Immunomodulators are natural or synthetic substances that help regulate or normalize the Address for immune system. Immunomodulators correct immune systems that are Correspondence out of balance. The benefits of immunomodulators stem from their ability to stimulate natural and adaptive defense mechanisms.A Acharya Nagarjuna number of disorders such as immunodeficiency state, autoimmune University, University disease, cancer and viral infection can be treated with College of immunostimulants drugs. The immune system is a part of body to Pharmaceutical detect the pathogen by using a specific receptor to produce Sciences, Nagarjuna immediately response by the activation of immune components cells, Nagar, Guntur-522510 cytokines, chemokines and also release of inflammatory mediator. India. They modulate and potentiate the immune system. E-mail: rajuph111 @gmail.com Keywords: Immunomodulators, Immunosuppressive, Immunology. INTRODUCTION The immune system is designed to processing of the antigen by the phagocytic protect the host from invading pathogens cells such as macrophages, monocytes, or and to eliminate disease. The primary object related cells. There are two types of immune in the past has been to suppress immune response are occurs in the human body: system to permit allotransplantation. I) Innate immune response Activation of immune system by “non-self” II) Adaptive immune response antigen (alloantigen) or “self” antigen (auto a. Humoral immunity antigen) is generally believed to require b. Cellular immunity American Journal of Phytomedicine and Clinical Therapeutics www.ajpct.org Ramya et al_________________________________________________ ISSN 2321 – 2748 I) Innate immune response: The like the temperature and pH of the body innate immune response is the first line of provide inappropriate living conditions for defense mechanism against physical, foreign organisms. Once pathogens have biochemical and cellular components. successfully entered the body, they are II) Adaptive immune response: addressed by the innate and/or the acquired a) Humoral immunity - Antibody or adaptive immune system3. Both systems production – killing extracellular organisms. consist of a multitude of cells and molecules b) Cell mediated immunity – that interact in a complex manner to detect cytotoxic / killer T-cells – killing virus and and eliminate pathogens4. Detection and tumour cells. Cellular immunity is expressed elimination depend upon chemical bonding: as cytotoxicity towards target cells by surfaces of immune system cells are covered activation of cytotoxic or “killer” T-cells. with various receptors, some of which The action of the cytotoxic T-cell is also chemically bind to pathogens, while others inhibited by adrenocorticosteroids1. But the bind to other immune system cells or humoral arm of the immune response is molecules to enable the complex signaling responsible for the production of the system that mediates the immune response5. antibodies; this is carried out by cells derived from the bone marrow (β-cell). Immunomodulators6 These are biological or synthetic Immunity2 substances that can stimulate, suppress or This may be defined as the body’s modulate any aspect of the immune system ability to identify and resist large numbers including both adaptive and innate arms of of infectious and potentially harmful the immune system6. microorganisms, enabling the body to prevent or resist diseases and inhibit organ Classification of immunomodulators and tissue damage2. The immune system is Clinically, immunomodulators can not confined to any one part of the body. be classified into the following three Immune stem cells, formed in the bone categories: marrow, may remain in the bone marrow Immunoadjuvants are used to until maturation or migrate to different body enhance the efficacy of vaccines and sites for maturation. Subsequently, most therefore could be considered specific immune cells circulate throughout the body, immune stimulants. Immunoadjuvants hold exerting specific effects. The immune the promise of being the true modulators of system has two distinct but overlapping the immune response. It has been proposed mechanisms with which to fight invading that they be exploited as selectors between organisms, the antibody-mediated defense cellular and humoral helper T1 (Th1) and system (humoral immunity) and the cell- helper T2 cells (Th2), immunoprotective, mediated defense system (cellular immunodestructive, and reagenic immunity). [immunoglobulin E (IgE)] versus IgG type immune responsesdposing a real challenge Immune systems3,4,5 to vaccine designers. The basic architecture of the immune Immunostimulants7 are inherently system is multilayered, with defenses on non-specific as they are envisaged as several levels. Most obvious and primary is enhancements to a body’s resistance to the skin: the first barrier against infection. infection. They can act through innate as Another is physiological, where conditions well as adaptive immune responses. In AJPCT[1][8][2013]628-644 Ramya et al_________________________________________________ ISSN 2321 – 2748 healthy individuals, the immunostimulants ultimately decreased fibrosis9. are expected to serve as prophylactic and Glucocorticoids can also reduce expression promoter agents, i.e., as of proinflammatory cytokines such as COX- immunopotentiators, by enhancing the basic 2 and NOS2. The influence of stressful level of immune response7. In the individual conditions on immune defense mechanisms with impairment of immune response, they is well documented as is the contribution of are expected to act as immunotherapeutic the HPA axis to the stress response. Stresses agents. such as injury, infection and disease result in Immunosuppressants3 are a the increased production of cytokines a structurally and functionally heterogeneous network of signalling molecules that group of drugs, which are often integrate actions of macrophages concomitantly administered in combination /monocytes, T lymphocytes and B regimens to treat various types of organ lymphocytes in mounting immune transplant rejection and autoimmune responses10. Among these cytokines diseases. interleukin (IL)-1, IL-6, and tumor necrosis factor-a (TNF-a) stimulate the HPA axis Drugs used for Immunomodulation8 with IL-1 having the broadest range of All drugs which modify immune actions. IL-1 stimulates the release of CRH response generally categorized as by hypothalamic neurons, interacts directly immunomodulators. These can either with the pituitary to increase the release of function as: ACTH and may directly stimulate the 1. Immunosuppressants adrenal gland to produce glucocorticoids. 2. Immunostimulants. Factors that are inhibited include Some of these can have both the components of the cytokine network, properties depending on which component including interferon-g (IFN-g), granulocy- of immune response they affect. There is temacrophage colony-stimulating factor also an upcoming generation of (GM-CSF), interleukins (IL-1, IL- 2, IL-3, immunosuppressants called tolerogens. IL-6, IL-8, and IL-12), and TNF-a. 1. Immunosuppressant drugs8 I. Inhibitors of Lymphocyte Gene Expression to Reduce Inflammatory Response Glucocorticoids: Mechanism of Action9,10 Multiple mechanisms are involved in the suppression of inflammation by glucocorticoids. Glucocorticoids inhibit the production by multiple cells of factors that are critical in generating the inflammatory response. As a result there is decreased Therapeutic Uses release of vasoactive and chemoattractive Acute transplant rejection, graft- factors diminished secretion of lipolytic and versus-host disease in bonemarrow proteolytic enzymes decreased extravasation transplantation, rheumatoid and other of leukocytes to areas of injury and arthritides, systemic lupus erythematosus, systemic dermatomyositis, psoriasis and AJPCT[1][8][2013]628-644 Ramya et al_________________________________________________ ISSN 2321 – 2748 other skin conditions, asthma and other with the cyclosporine/cyclophilin complex. allergic disorders, inflammatory bowel This prevents NFAT dephosphorylation disease, inflammatory ophthalmic diseases. such that NFAT does not enter the nucleus gene transcription is not activated and the T Adverse Effects lymphocyte fails to respond to specific Growth retardation in children, antigenic stimulation. Cyclosporine also avascular necrosis of bone, osteopenia, increases expression of transforming growth increased risk of infection, poor wound factor-b (TGF-b), a potent inhibitor of IL-2- healing, cataracts, hyperglycemia, and stimulated T-cell proliferation and hypertension11. generation of cytotoxic T lymphocytes (CTL). II. Inhibitors of Lymphocyte Signaling to Prevent Immune Cell Activation and Pharmacokinetics8