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Do antibodies remain in the blood after the pathogen is gone?

Discussion in 'MCAT Study Question Q&A' started by DenTony11235, May 15, 2014.

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  1. 403710

    403710 Guest 5+ Year Member

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    I think they do, but not 100% sure. Can anyone verfiy this with some source?

    Do antibodies just swim around in the blood unattached to B-cells way after a certain antigen has passed?
     
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  3. Czarcasm

    Czarcasm Hakuna matata, no worries. 2+ Year Member

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    If I recall correctly from my Immunology Class, Naive B Cells become 'activated' when it recognizes a pathogen (it's antigen), and it undergoes proliferation and differentiation in the lymph nodes to form Memory B Cells and Plasma B Cells. The Plasma B Cells exit to various parts of the body to deal with the pathogen by secreting antibodies and these antibodies deal with the pathogen by different means: opsonization/phagocytosis, complement, etc.

    naive B cells generally last 3 weeks. If they aren't activated they die.
    plasma cells (activated naive B cells), last an approx 3-4 weeks (not 100% sure of range) and continue to secrete antibodies during that period.

    But the antibodies they secrete, depending on which the type, can last anywhere between a few weeks to a few months. The antibodies themselves though (which are proteins) definitely don't last forever (like all proteins). Eventually certain suppressor cells kill off plasma cells after the response has taken its course, and all that remains are a few memory cells, which are reactivated again should the pathogen invade the body in the future. These memory cells are the reason why the second and later response are always much faster because the initial response.

    Also, unlike naive B cells which don't last more than a few weeks, naive T cells last a long freakin time and the reason for this is because of the involution of our thymus through adulthood. T cells are essential to activating B cells and without them, we'd definitely be in an immune suppressed state.
     
    Last edited: May 15, 2014
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  4. 403710

    403710 Guest 5+ Year Member

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    Thank you for this. The information i was looking for was there. Also, didn't know that T-cells live longer. Much obliged.
     
    Czarcasm likes this.
  5. StIGMA

    StIGMA Doctor Professor 7+ Year Member

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    B cells that responded to an infection (with recombination to a specific antibody) can remain for your whole life (not necessarily the parent cell, but its progeny, "memory B cells"). This is one reason why vaccines work for years and not weeks- you continue to produce antibodies to the antigen. 1918 flu survivors have B cells from that infection that continue to produce antibodies close to 90 years after infection- see this Nature article from 2008. http://www.ncbi.nlm.nih.gov/pubmed/18716625
     
    Last edited: May 16, 2014
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  6. dyspareunia

    dyspareunia

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    Plasma cells do not "exit to various parts of the body". They reside either in the lymph node (or spleen) where they matured or they migrate to the bone marrow. IgG has the longest half-life and it only lasts for about 25 days. No antibody lasts for a few months.
     
  7. Czarcasm

    Czarcasm Hakuna matata, no worries. 2+ Year Member

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    The "various parts" I was referring to was the lymph node, spleen, and bone marrow; IgG's half a half-life of 3 weeks, meaning by 3 weeks, a portion of the initial amount of IgG's in the plasma will be reduced by half as much. There's still a fraction that remains that exists in plasma (longer than the 3 week period), but this largely decreases over time.
     

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