Isotype switching The doctor went on to explain that lgM was the first kind of a
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Isotype switching The doctor went on to explain that lgM was the first kind of antibody made by B cells in response to the appearance of an antigen, and that Daniel appeared to be making these immunoglobulins just fine. However, it appeared his immune system failed to undergo immunoglobulin isotype switching. Susarn Questions 3. What is an antigen? 4. What is immunoglobulin isotype switching? 5. How does the failure of immunological isotype switching explain the lack of lgG, IgA, and IgE in Daniel's blood? 6. Is this the only explanation for the lack of lgG, IgA, and lgE in Daniel's blood? 7. Why do you think the doctor suspected the need for genetic testing?Explanation / Answer
3) An antigen is any agent, whether foreign or self which is capable of interacting with the antibodies produced by the body's immune system and bring about an immune response. It can be any chemical substance or a pathogen.
4) Immunoglobulin class switching or isotype switching is the process by which the production of immunoglobulins by B cells changes from one type to another, such as from the isotype IgM to IgG or IgA etc. It is a DNA recombination event during which the constant-region portion of the antibody heavy chain is changed, but the variable region of the heavy chain stays the same.
5) A naive, mature B cell is capable of producing IgM and IgD which are the first two heavy chain segments in the immunoglobulin locus. After activation by antigen, these B cells proliferate. If these activated B cells encounter specific signaling molecules via their CD40 and cytokine receptors (both modulated by T helper cells), they undergo antibody class switching to produce IgG, IgA or IgE antibodies. Thus, if isotype switching is not performed correctly or undergoes a complete failure, then the affected person will remain deficient in IgG, IgA or IgE antibodies. Without signal transduction, the B cell does not undergo isotope switching and thus is only producing IgM and IgD, which is what is happening with Daniel.
6) No, it cannot be definitely said that this is the only reason for the lack of IgG, IgA and IgE antibodies, since only primary analysis has been done. On the basis of preliminary analysis, lack of isotype switching seems to be the only reason for the deficiency of IgG, IgA and IgE, however unless and until a definite genetic testing is not conducted, we cannot say that this is the only reason for it.
7) Since, Daniel's body is perfectly capable of producing IgM, it means that his immune system is working just fine. However, there is a distinct lack of other immunoglobulins which are a result of Immunoglobulin class switching which is a DNA recombination event. This suggests that maybe Daniel's problem is associated with genetics instead of immune system. This is why the doctor suspected the need for genetic testing.
8) As members of a healthcare team, genetic counselors provide information and support to familiesaffected by or at risk for a genetic disorder. They serve as a central resource of information. Here, their role is to closely look at Daniels genes and see if this immunodeficiency has been passed down from the parents.
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