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متلازمة فرط Hyper-IgM Syndrome IgM


متلازمة فرط Hyper-IgM Syndrome IgM

المعلومة

The most common molecular abnormality in patients with Hyper-IgM Syndrome is deficient expression of CD40L (CD154) in helper T cells.

الشذوذ الجزيئي الأكثر شيوعا عند المرضى المصابين بمتلازمة فرط الـIgM هو التعبير الناقص للـ CD40L في الخلايا التائية المساعدة .

المرجع

Virella G., Introduction to Medical Immunology, 4th Edition

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السنة الخامسة


So what is hyper IgM desease?

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DAM

Hyper-IgM Syndrome
  • Is a type of Dysgammaglobulinemia (Stedman : An immunoglobulin abnormality, a disturbance of the percentage distribution of gamma-globulins or selective deficiency of one or more immunoglobulins.)
  • Hyper-IgM syndrome may be X-linked (70%) or autosomal recessive.
  • The most common molecular abnormality in patients with Hyper-IgM Syndrome is deficient expression of CD40L (CD154) in helper T cells:-
    • It is an X-linked dificiency.
    • X-linked Hyper-IgM syndrome is characterized by a deficiency of IgG, IgA, and IgE, and elevated levels of IgM, sometimes as high as 10 mg/ml (normal IgM concentration is 1.5 mg/ml).
    • Class switching and formation of memory B cells both require contact with TH cells by a CD40–CD40L interaction. The absence of this interaction in XHIM results in the loss of class switching to IgG, IgA, or IgE isotypes and in a failure to produce memory B cells. So, patients with XHIM present with recurrent pyogenic infections (e.g., S. pneumoniae, N. meningitidis, H. influenzae, S. aureus), owing to low levels of opsonizing IgG levels.
    • Macrophage activation also requires the contact with TH cells by CD40-CD40L interaction, so these patients are also suseptible to a variety of pathogens that require intact DTH (Delayed-Type Hypersensitivity) response, including Pneymocystis Carinii.
    • XHIM patients often have high levels of autoantibodies (IgM) to neutrophils, platelets, and red blood cells. Resulting in autoimmune hemolytic anemia, thrombocytopenia or neutropenia.
    • The treatment of choice is a human leukocyte antigen (HLA)–identical sibling bone marrow transplant at an early age.
      Treatment for this condition also includes monthly Intravenous administration of gamma globulin.
  • References:-
    • ROBBINS Basic Pathology, 7th Ed.
    • Introduction to Medical Immunology, 4th Ed.
    • Kuby Immunology, 5th Ed.
    • Fundamental Immunology, 5th Ed.
    • Color Atlas of Immunology
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