Disease Of Immunity

Disease of immunity DAP

Immune system






Immunodeficiency infections. Ex AIDS Tumors; on the other hand, a hyperactive immune system may cause fatal disease, as in the case of an overwhelming allergic reaction to the sting of a bee. The immune system may lose its normal capacity to distinguish self from non-self, resulting in immune reactions against one's own tissues and cells (autoimmunity). Ex ITP

Immune system









Responsible for safeguarding the body from disease causing microorganism. It is a part of a complex system of Host Defense Host defense : Innate/natural and acquired/adaptive Innate defense : physical (skin) and chemical barriers (Lysozyme found in mucus, saliva, tears and HCl), complex defense, cells, and natural killer lymphocyte. Innate immunity is the first line of defense, because it is always ready Acquired defense : caused by foreigners encounter the body ( virus or bacteria)

Immune respons









There are two main types of adaptive immunity—cellmediated (or cellular) immunity _T cell, which is responsible for defense against intracellular microbes, and humoral immunity- B cell, which protects against extracellular microbes and their toxins . Cellular immunity is mediated by T (thymus-derived) lymphocytes, mature in Thymus Humoral immunity is mediated by B (bone marrowderived, mature in marrow) lymphocytes and their secreted products such as lymphokine (IL-2, IL-4, Interferon-8) Hummoral immunity = antibody mediated response

Antigen
Substance

can induce immune respons
T and B lymphocyte have specific receptors to specific antigen molecular shapes (epitop)
In B cells, the receptors are called by antibody (an immunoglobuline)
Hapten?Carrier?

Macrophage
Macrophages

are immune and inflammatory response
Macrophages lack receptors of specific antigens, but they have specific receptors for c region of immunoglobuline (Fc)
Macrophages ingest and process the antigen

T cell


Types of T Cells




The two main types of T cells are cytotoxic T cells and helper T cells. Cytotoxic T (Tc) cells can bring about the destruction of antigenbearing cells, such as virus-infected or cancer cells. Cancer cells also have nonself proteins. Cytotoxic T cells are responsible for so-called cell-mediated immunity Helper T (Th) cells regulate immunity by secreting cytokines, the chemicals that enhance the response of other immune cells.




MHC
The

T cell antigen receptor only in ascociation with specific cell surface molecules. Also known as HLA
Every person receives one set of MHC genes from each parent. Both sets are expreesed on individual cells

Natural Killer Cells killer (NK) cells kill virusinfected cells and tumor cells by cell-tocell contact. They are large, granular lymphocytes with no specificity and no memory. Their number is not increased by prior exposure to any kind of cell.


Natural

Complement system














Composed of a number of blood plasma proteins designated by the letter C and a subscript. A limited amount of activated complement protein is needed because a cascade effect occurs: Each activated protein in a series is capable of activating many other proteins. The complement proteins are activated when pathogens enter the body. The protein “complement” certain immune responses, which accounts for their name. Certain other complement proteins join to form a membrane attack complex that produces holes in the walls and plasma membranes of bacteria. Fluids and salts then enter the bacterial cell to the point that it bursts. Complement system includes 20 serum proteins There are 2 pathways : classic and alternate Classis : Ig M and IgG binds with the antigen and activate C1 next turn to activates C4, C2 and C3 Alternate : bacterial cell membranes activates C3, and next to C5 and C9

Cytokines and Immunity







LMWP involved in communications berween macrophage and lymphocyte Whenever cancer develops, it is possible that cytotoxic T cells have not been activated. With this possibility in mind, cytokines have been used as immunotherapeutic drugs to enhance the ability of T cells to fight cancer. Interferon, and also interleukins, which are cytokines produced by various white blood cells, are also being administered for this purpose.

Pathophysiology manifestation
There

are 3 basic reactions : hypersensitivity, autoimmune response and alloimmune response

Hypersensitivity







Exogenous antigens occur in dust, pollens, foods, drugs, microbiologic agents, chemicals, and many blood products used in clinical practice. The immune responses that may result from such second exposure exogenous antigens take a variety of forms, such as itching of the skin, to potentially fatal diseases, such as bronchial asthma. The various reactions produced are called hypersensitivity reactions, and tissue injury in these reactions may be caused by humoral or cell-mediated immune mechanisms. Injurious immune reactions may be evoked not only by exogenous environmental antigens, but also by endogenous tissue antigens. Some of these immune reactions are triggered by homologous antigens that differ among individuals with different genetic backgrounds. Transfusion reactions and graft rejection are examples of immunologic disorders evoked by homologous antigens.

Type 1

Systemic Anaphylaxis






Systemic anaphylaxis is characterized by vascular shock, widespread edema, and difficulty in breathing. In humans, systemic anaphylaxis may occur after administration of foreign proteins (e.g., antisera), hormones, enzymes, polysaccharides, and drugs (such as the antibiotic penicillin The severity of the disorder varies with the level of sensitization. Extremely small doses of antigen may trigger anaphylaxis, for example, the tiny amounts used in ordinary skin testing for various forms of allergies. Within minutes after exposure, itching, hives, and skin erythema appear, followed shortly thereafter by a striking contraction of respiratory bronchioles and respiratory distress. Laryngeal edema results in hoarseness. Vomiting, abdominal cramps, diarrhea, and laryngeal obstruction follow, and the patient may go into shock and even die within the hour. The risk of anaphylaxis must be borne in mind when certain therapeutic agents are administered. Although patients at risk can generally be identified by a previous history of some form of allergy, the absence of such a history does not preclude the possibility of an anaphylactic reaction.

Type 2

Type 3

Type 4

Autoimmune disease


Body’s

normal defense become self destructive, recognizing self antigen as a foreign
The causes are not clearly understood

Alloimmune response


Commonly

happens in transplantation or

transfusion
The recipients react to antigens, primarily the HLA of the donor cells
Commonly ascociated with type 2 hypersensitivity reaction

Immunodeficiency
An

absent or depressed immune response increses susceptability to infection.
Defect of T cell, B cell, lymphoid tissue

Disorder







AIDS Caused by gradual destruction of T cell HIV infection of macrophages has three important implications. First, monocytes and macrophages represent a veritable virus factory and reservoir, whose output remains largely protected from host defenses. Second, macrophages provide a safe vehicle for HIV to be transported to various parts of the body, including the nervous system. Third, in late stages of HIV infection, when the CD4+ T-cell numbers decline greatly, macrophages may be an important site of continued viral replication.In contrast to tissue macrophages, the number of monocytes in circulation infected by HIV is low, yet there are unexplained functional defects that have important consequences for host defense. These defects include impaired microbicidal activity, decreased chemotaxis, decreased secretion of IL-1, inappropriate secretion of TNF, and, most important, poor capacity to present antigens to T cells.

Homework
Please

learn about asthma alergic