WBR0681: Difference between revisions

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|MainCategory=Immunology
|MainCategory=Immunology
|SubCategory=General Principles
|SubCategory=General Principles
|MainCategory=Immunology
|MainCategory=Immunology
|MainCategory=Immunology
|MainCategory=Immunology
|MainCategory=Immunology
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[[Image:WBR0681.png|400px]]
[[Image:WBR0681.png|400px]]
|Explanation=The patient has elevated levels of IgM, which is a pentamer that is produced in the immediate response against pathogens. The shape of IgM is important to allow it to maximally trap antigens. Given the patient's elevated IgM, he most likely has hyper IgM syndrome, which is commonly due to a defective CD40L on helper T cells that prevents immunoglobulin class switching, leading to a deficiency in all other classes of immunoglobulin and high serum concentration of IgM. Patients with hyper IgM syndrome typically complain of recurrent pyogenic infections due to inability to mount an appropriate immune response.
|Explanation=The patient has elevated levels of IgM, which is a pentamer that is produced in the immediate response against pathogens. The shape of IgM is important to allow it to maximally trap antigens. Given the patient's elevated IgM, he most likely has hyper IgM syndrome, which is commonly due to a defective CD40L on helper T cells that prevents immunoglobulin class switching, leading to a deficiency in all other classes of immunoglobulin and high serum concentration of IgM. Patients with hyper IgM syndrome typically complain of recurrent pyogenic infections due to inability to mount an appropriate immune response.
Educational Objective: IgM is a pentamer. It is increased in hyper IgM syndrome, that is commonly caused by  a defective CD40L on helper T cells.
|AnswerA=Defect in B-cell maturation
|AnswerA=Defect in B-cell maturation
|AnswerAExp=Common variable immunodeficiency (CVID) is due to a defect in B-cell maturation.
|AnswerAExp=Common variable immunodeficiency (CVID) is due to a defect in B-cell maturation.
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|AnswerE=Defective CD40L on helper T cells
|AnswerE=Defective CD40L on helper T cells
|AnswerEExp=Hyper-IgM syndrome is characterized by defective CD40L on helper T cells
|AnswerEExp=Hyper-IgM syndrome is characterized by defective CD40L on helper T cells
|EducationalObjectives=IgM is a pentamer. It is increased in hyper IgM syndrome, that is commonly caused by  a defective CD40L on helper T cells.
|References=First Aid 2015 page 205
|RightAnswer=E
|RightAnswer=E
|WBRKeyword=hyper, IgM, hyper-IgM, recurrent, infection, infections, CD40L, class, switching, immunoglobulin, pentamer
|WBRKeyword=Hyper IgM, hyper-IgM, Recurrent infection, Infections, CD40L, Class switching, Immunoglobulin, Pentamer
|Approved=No
|Approved=Yes
}}
}}

Revision as of 03:51, 13 January 2015

 
Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Immunology
Sub Category SubCategory::General Principles
Prompt [[Prompt::A 1 year old boy is brought by his mother for recurrent infections. Following appropriate work-up, the patient is found to have very high serum concentration of one immunoglobulin class that normally exists in the form shown in the image below. The patient also has deficient serum concentrations of all other immunoglobulin classes. Which of the following best characterizes the patient's condition?

]]

Answer A AnswerA::Defect in B-cell maturation
Answer A Explanation AnswerAExp::Common variable immunodeficiency (CVID) is due to a defect in B-cell maturation.
Answer B AnswerB::Inability of T cells to reorganize actin cytoskeleton
Answer B Explanation AnswerBExp::Wiskott-Aldrich syndrome is characterized by the inability of T cells to reorganize actin cytoskeleton.
Answer C AnswerC::Failure of Th1 cells to produce IFN-gamma
Answer C Explanation AnswerCExp::Hyper-IgE syndrome is characterized by the failure of Th1 cells to produce IFN-gamma.
Answer D AnswerD::Defect of the BTK gene
Answer D Explanation AnswerDExp::X-linked (Bruton's) agammaglobulinemia is characterized by a defective BTK gene.
Answer E AnswerE::Defective CD40L on helper T cells
Answer E Explanation AnswerEExp::Hyper-IgM syndrome is characterized by defective CD40L on helper T cells
Right Answer RightAnswer::E
Explanation [[Explanation::The patient has elevated levels of IgM, which is a pentamer that is produced in the immediate response against pathogens. The shape of IgM is important to allow it to maximally trap antigens. Given the patient's elevated IgM, he most likely has hyper IgM syndrome, which is commonly due to a defective CD40L on helper T cells that prevents immunoglobulin class switching, leading to a deficiency in all other classes of immunoglobulin and high serum concentration of IgM. Patients with hyper IgM syndrome typically complain of recurrent pyogenic infections due to inability to mount an appropriate immune response.

Educational Objective: IgM is a pentamer. It is increased in hyper IgM syndrome, that is commonly caused by a defective CD40L on helper T cells.
References: First Aid 2015 page 205]]

Approved Approved::Yes
Keyword WBRKeyword::Hyper IgM, WBRKeyword::hyper-IgM, WBRKeyword::Recurrent infection, WBRKeyword::Infections, WBRKeyword::CD40L, WBRKeyword::Class switching, WBRKeyword::Immunoglobulin, WBRKeyword::Pentamer
Linked Question Linked::
Order in Linked Questions LinkedOrder::