b) Reactions to Transplantation  Transplants may be attacked by T cells, macrophages, and complement-fixing antibodies.  Transplants to privileged sites do not cause an immune response.  Stem cells may allow therapeutic cloning to avoid rejection.

Grafts  Autograft: Use of one's own tissue.  Isograft: Use of identical twin's tissue.  Allograft : Use of tissue from another person.  Xenotransplantation product : Use of non-human tissue. Graft-versus-host disease can result from transplanted bone marrow that contains immuno competent cells.Graft-versus-host disease can result from transplanted bone marrow that contains immuno competent cells.

Immunosuppression drugs prevents an immune response to transplanted tissues  Cyclosporine suppresses IL-2.  Mycophenolate mofetil inhibits T cell and B cell reproduction.  Sirolimus blocks IL-2.

c)Immune Deficiencies  Congenital (primary):  Congenital (primary): Due to defective or missing genes.  Selective IgA immunodeficiency.  Severe combined immunodeficiency.  Acquired (secondry):  Acquired (secondry): Develop during an individual's life, due to drugs, cancers, infections.  Artificial: Immunosuppression drugs.  Natural: HIV infections.

Secondary Immunodeficiency 1.Secondary, or acquired, immunodeficiency diseases are acquired during life, e.g. the result of malignancies, advanced age, certain infections, immunosuppressive drugs, or malnutrition. death 2.Infections like measles virus, causes the death of many lymphoid cells, leaving the body temporarily open to other infections. 3.Syphilis, leprosy, and malaria deplete the T-cell population, leaving the body deficient in cell- mediated immunity.

 The thymus fails to develop and, as a result, the T-cells fail to differentiate and are absent. eukaryotic pathogens r obligate intracellular bacteria  These patients are very susceptible to infections by eukaryotic pathogens such as fungi, as well as viruses and obligate intracellular bacteria. certain malignant tumors.  In addition, they are prone to develop certain malignant tumors.  Treatment: Thymic graft, administration of thymus extracts or purified thymic hormones.

d) Autoimmune Diseases  Clonal deletion during fetal development ensures self-tolerance.  Autoimmunity is loss of self-tolerance.  Normally recognizes itself antigens and does not attack its own tissues.  Normally, the body's immune system usually recognizes itself antigens and does not attack its own tissues.  However, a growing number of diseases are suspected of being caused by an autoimmune process, meaning that the immune system of the body is responding to its own tissues as foreign.

Diseases Related to Specific HLAs

SOME DISEASES SUSPECTED OF BEING AUTOIMMUNE Disease Main Areas Affected Rheumatoid arthritis Joints Lupus erythromatosisJoints, skin, heart, kidneys Graves' diseaseThyroid Diabetes mellitusPancreas Myasthenia gravisMuscle nerves Myasthenia gravisMuscle nerves Sympathetic ophthalmia Eyes Sympathetic ophthalmia Eyes Multiple sclerosis Brain, spinal cord Hemolytic anemiaBlood

 Myasthenia gravis is an example of a disease in which humoral antibodies are involved.  Sympathetic ophthalmia is an example of a disease in which delayed hypersensitivities are involved.  Autoantibodies have been demonstrated against gamma globulins (IgG) in rheumatoid arthritis and against cell nuclei in lupus erythematosus.

1- Myasthenia Gravis blocking  An individual with myasthenia gravis has muscle weakness. The cause of the disease is known to be the production of antibodies to the acetylcholine receptor proteins that are present on muscle membranes. Thereby blocking access of acetylcholine to these receptors.  In babies born to Myasthenia gravis mothers, the babies not experience muscle weakness due to IgG antibodies cross the placenta. Fortunately, the effect is not permanent since these IgG antibodies decay within a few months and the babies are no longer affected.

 Treatment of Myasthenia gravis includes enzyme cholinesterase 1.Drugs that inhibit the enzyme cholinesterase, allowing acetylcholine to accumulate so that contact with receptors can occur. 2. Immunosuppressive 2. Immunosuppressive medications. 3.Thymectomy 3.Thymectomy (removal of the thymus glands) are helpful in many cases, although the role of the thymus this disease is not understood.

Sympathetic Ophthalmia 1.Sympathetic Ophthalmia is a condition in which a penetrating wound of one eye produces blindness. 2.Unfortunately, the destructive process is not limited to the injured eye but soon appears in the healthy eye. loss of vision shrinkage of the eye 3.It leads to progressive loss of vision and eventual shrinkage of the eye.

Pemphigus  Pemphigus  Pemphigus is characterized by blisters on the skin and mucous membranes.  The blisters rupture easily, leaving open sores, which may ooze and become infected.  The signs and symptoms of the three main types of pemphigus differ depending on the type.  Pemphigus vulgaris  Pemphigus vulgaris The most common form, it usually begins with blisters in the mouth, which then erupt on skin.  Blisters also can break out on the mucous membranes of genitals. The blisters typically are painful, but don't itch.

 Pemphigus foliaceus: This type doesn't usually affect mucous membranes. The blisters, which usually begin on face and scalp and later erupt on chest and back, usually aren't painful. They tend to be crusty and itchy.  Paraneoplastic pemphigus : This form causes painful sores on mouth and lips and in esophagus, as well as skin lesions. This form of pemphigus also can cause lesions in lungs, resulting in progressive lung disease and making it difficult to breath (dyspnea).

Causes  The exact cause of pemphigus is unknown, but it may be an autoimmune disorder.  Normally, immune system attacks foreign invaders, such as harmful viruses and bacteria.  But in pemphigus, immune system produces antibodies that attack healthy cells in the skin or mucous membranes, specifically proteins called desmogleins. (desmogleins bind skin cells to each other. )  The antibodies cause separation of the cells of the top layer of the skin (epidermis).  This reaction is known as acantholysis.

Risk factors  Pemphigus isn't contagious, and there's no way to predict who'll get it. However, the risk increases if:  The ages between 30 and 60.  Mediterranean or Jewish descent.  have another autoimmune condition, particularly myasthenia gravis, (a chronic disorder characterized by muscle weakness and fatigue), or thymoma (a tumor of the thymus).

Pemphigus

Pemphigus