Immunodeficiency Diseases: 16th lecture Immunodeficiency Diseases: Hyposensitivity of the Immune System لتحميل المحاضرة ادخل الرابط التالي https://app.box.com/folder/19854514021 Dr. Talib Hassan College of Medicine ThiQar University

Immunodeficiency Diseases 16th lecture Immunodeficiency Diseases In many cases, the nature have provided penetrating insights into the exact functions of certain cells, tissues, and organs because of the specific signs and symptoms shown by the immuno-deficient individuals. The predominant consequences of immunodeficiencies are recurrent, overwhelming infections, often with opportunistic microbes. Immunodeficiencies fall into two general categories: primary diseases, present at birth (congenital) and usually stemming from genetic errors secondary diseases, acquired after birth and caused by natural or artificial agents. stemming تنبثق

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PRIMARY IMMUNODEFICIENCY DISEASES 16th lecture PRIMARY IMMUNODEFICIENCY DISEASES Deficiencies affect both specific immunities such as antibody production and less specific ones such as phagocytosis. In many cases, the deficiency is due to an inherited abnormality. Because the development of B cells and T cells departs at some point, an individual can lack one or both cell lines. It must be emphasized, however, that some deficiencies affect other cell functions. For example a T-cell deficiency can affect B-cell function because of the role of T helper cells. In some deficiencies, the lymphocyte is completely absent or is present at very low levels, whereas in others, lymphocytes are present but do not function normally. departs ينحرف

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Deficiencies in B-Cell Development or Expression 16th lecture Deficiencies in B-Cell Development or Expression Genetic deficiencies in B cells usually appear as an abnormality in immunoglobulin expression. In some instances, only certain immunoglobulin classes are absent; in others, the levels of all types of immunoglobulins (Ig) are reduced. A significant number of B cell deficiencies are X-linked

The term agammaglobulinemia literally means the absence of gamma globulin, the primary fraction of serum that contains immunoglobulins. Because it is very rare for Ig to be completely absent, some physicians prefer the term hypogammaglobulinemia.

Both sex-linked and autosomal recessive types of this rare syndrome occur. In both cases, mature B cells are absent, the level of antibodies is greatly reduced, and lymphoid organs are incompletely developed. T-cell function in these patients is usually normal. The symptoms of recurrent, serious bacterial infections (pyogenic cocci, Pseudomonas, and Haemophilus influenza) usually appear about 6 months after birth. Many Ig-deficient patients can have recurrent infections with viruses and protozoa, as well. Patients often manifest a wasting syndrome and have a reduced lifespan. The current treatment for this condition is passive immunotherapy with immune serum globulin and continuous antibiotic therapy. wasting اضاعة

The lack of a particular class of immuno-globulin is a relatively common condition. IgA deficiency is the most prevalent, occurring in about one person in 600. Such persons have normal quantities of B cells and other immunoglobulins, but they are unable to synthesize IgA. Consequently, they lack protection against local microbial invasion of the mucous membranes and suffer recurrent respiratory and gastrointestinal infections.

Clinical Deficiencies in T-Cell Development or Expression 16th lecture Clinical Deficiencies in T-Cell Development or Expression Due to their critical role in immune defenses, a genetic defect in T cells results in a broad spectrum of disease, including severe opportunistic infections, wasting, and cancer. In fact, a dysfunctional T-cell line is usually more devastating than a defective B-cell line, because T helper cells are required to assist in most specific immune reactions. The deficiency can occur anywhere along the developmental spectrum, from thymus to mature, circulating T cells. Wasting تبذير devastating مدمر

Abnormal Development of the Thymus 16th lecture The most severe of the T-cell deficiencies involve the congenital absence or immaturity of the thymus gland. Thymic aplasia, or DiGeorge syndrome, results when the embryonic third and fourth pharyngeal pouches fail to develop. Some cases are associated with a deletion in chromosome 22. Aplasia عدم تنسج

The accompanying lack of cell-mediated immunity makes children highly susceptible to persistent infections by fungi, protozoa, and viruses. Common, usually benign, childhood infections such as chickenpox, measles, or mumps can be overwhelming and fatal in these children. Even vaccinations using attenuated microbes pose a danger. Other symptoms of thymic failure are reduced growth, wasting of the body, unusual facial characteristics, and an increased incidence of lymphatic cancer. These children can have reduced antibody levels, and they are unable to reject transplants. The major therapy for them is a transplant of thymus tissue.

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Severe Combined Immunodeficiencies: Dysfunction in B and T Cells 16th lecture Severe Combined Immunodeficiencies: Dysfunction in B and T Cells Severe combined immunodeficiencies (SCIDs) are the most dire and potentially lethal of the immunodeficiency diseases because they involve dysfunction in both lymphocyte systems. Some SCIDs are due to the complete absence of the lymphocyte stem cell in the marrow; others are attributable to the dysfunction of B cells and T cells later in development. Infants with SCID usually manifest the T-cell deficiencies within days after birth by developing candidiasis, sepsis, pneumonia, or systemic viral infections. This debilitating condition appears to have several forms. In the two most common forms, agammaglobulinemia and thymic a lymphoplasia, the numbers of all types of lymphocytes are extremely low, the blood antibody content is greatly diminished, and the thymus and CMI are poorly developed. dire رهيب

16th lecture A rarer form of SCID is adenosine deaminase (ADA) deficiency, caused by an autosomal recessive defect in the metabolism of adenosine. Infants with ADA deficiency are subject to recurrent infections and severe wasting typical of severe deficiencies. A small number of SCID cases are due to a developmental defect in receptors for B and T cells. An X-linked deficiency in IL- receptors was responsible for the disease of David, the child in the “plastic bubble’’. Another newly identified condition, bare lymphocyte syndrome, is caused by the lack of genes that code for class II MHC receptors. Because of their profound lack of specific adaptive immunities, SCID children require the most rigorous kinds of aseptic techniques to protect them from opportunistic infections. rigorous صارم

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16th lecture Some infants can benefit from fetal liver or bone marrow grafts. Although transplanting compatible bone marrow has been about 50% successful in curing the disease, it is complicated by GVHD. The condition of some ADA deficient patients has been partly corrected by periodic transfusions of blood containing large amounts of the normal enzyme. A more lasting treatment for both X-linked and ADA types of SCID has been found in gene therapy—insertion of a gene to replace the defective gene. Several children have apparently been cured by transfecting their bone marrow stem cells with the normal gene for ADA.

SECONDARY IMMUNODEFICIENCY DISEASES 16th lecture SECONDARY IMMUNODEFICIENCY DISEASES Secondary acquired deficiencies are caused by one of four general agents: (1) Infection. (2) Organic disease. (3) Chemotherapy. (4) Radiation. AIDS a syndrome caused when several types of immune cells, including T helper cells, monocytes, macrophages, and antigen presenting cells, are infected by the human immunodeficiency virus (HIV). It is generally thought that the depletion of T helper cells and functional impairment of immune responses ultimately account for the cancers and opportunistic protozoan, fungal, and viral infections associated with this disease.

infections can deplete immunities (measles, leprosy, and malaria). 16th lecture infections can deplete immunities (measles, leprosy, and malaria). Cancers that target the bone marrow or lymphoid organs can be responsible for extreme malfunction of both humoral and cellular immunity. leukemia, the massive number of cancer cells compete for space and literally displace the normal cells of the bone marrow and blood. Plasma cell tumors produce large amounts of nonfunctional antibodies thymus gland tumors cause severe T-cell deficiencies.

An ironic outcome of life-saving medical procedures is the possible suppression of a patient’s immune system. For instance, some immunosuppressive drugs that prevent graft rejection by T cells can likewise suppress beneficial immune responses. Although radiation and anticancer drugs are the first line of therapy for many types of cancer, both agents are extremely damaging to the bone marrow and other body cells. ironic outcome نتائج ساخرة

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